Sig MPX?

[Up1911Fan]

I realize it's a pistol, but looking at it in the SBR role. Anyone have any experience with them?

[Gray222]

Buddy is a gunsmith at a local shop/range. He saw two in the same month that had failures with suppressors. One wouldnt work, even following the manual to the letter, other wouldnt feed next round.

[SamuelBLong]

Both my buddy and me have had good luck with ours.

No issues with running it suppressed with a 3 lug adapter


Sent from my iPhone using Tapatalk

[Default.mp3]

No issues with running it suppressed with a 3 lug adapterIs it as overgassed as some people make it out to be, and what can do you use? How is the charging handle, being as loose as it is? Gut impression, would you trust it in a duty roll?

I seriously want to get an MPX and SBR it to a K-format, as totally impractical as it might be, mainly because I want to have a "legitimate" reason to have a pistol suppressor, and have the ability to fold up a long gun inside a messenger bag. Will have to see if a magwell grip is viable with such a thing though, since I'd probably be putting an X300U where the factory VFG/handstop thing goes.

[Sigfan26]

I've shot a couple of them with Silencerco Octane suppressors attached without issue. Favorite "subgum " style weapon I've fired.

[JSGlock34]

The recent NFA changes are driving me to add a 9mm SBR to the safe sooner rather than later. I've long been debating the merits of acquiring the MPX vs. a MP5 clone (likely the Zenith Z-5RS). The MP5 design is timeless but the future modularity of the MPX is very compelling. The MPX seems a bit more mature now that 'GEN2' has arrived. Has anyone fired one of these suppressed? How's the gas? I have a AAC Ti-Rant 9 and a 3-lug adapter that would go on whatever I pick up. This is undoubtedly a fun gun; I've got the other major bases covered.

[GJM]

Is the CZ Evo the Glock 19 of this category?

[Chuck Haggard]

Is the CZ Evo the Glock 19 of this category?

None of the people I know with the CZ have one that works.

[Josh Runkle]

None of the people I know with the CZ have one that works.

Like the mpx, the evo is just now releasing a gen 2 as well, as I understand it. Perhaps that will include some actual improvements.

[SteveB]

30 minute video comparison MPX and EVO. Interesting stuff on suppressors and overgassing.

https://www.full30.com/video/166b7f86e62a6fdcf61716eb67b5d66b

[gtmtnbiker98]

30 minute video comparison MPX and EVO. Interesting stuff on suppressors and overgassing.

https://www.full30.com/video/166b7f86e62a6fdcf61716eb67b5d66bI stopped once I seen who made the video.

[GJM]

None of the people I know with the CZ have one that works.

I would be interested in as much detail as you can share -- number of Evos, type problems, etc., as this is the first mention I have ever heard of Evo reliability issues?

[GJM]

Like the mpx, the evo is just now releasing a gen 2 as well, as I understand it. Perhaps that will include some actual improvements.

Pretty modest changes on the new Evo (thread sizing and FDE option, that I recall), and no mention of anything related to function.

[SteveB]

Pretty modest changes on the new Evo (thread sizing and FDE option, that I recall), and no mention of anything related to function.

There's also the new carbine; with an improved (M-LOK?) fore end, it might offer a different path to an SBR - just cut and thread the barrel.

[SteveB]

I stopped once I seen who made the video.

Don't know the man.

[ranger]

Just got back from range with friend who has a SIG MPX pistol that he has SBR'd. Very nice. Running an Aimpoint H1 dot. I suspect it is a GEN1. It is overgassed and it really slings the brass. His has a folding and retracting SIG stock (apparently a new option). 8 inch barrel. We were on the IDPA bay at our private range and I really enjoyed running it on the plate racks and other steel. Definitely nice to shoot and I think it may be "smoother" shooting the gas operated MPX versus my blowback 9mm AR. Nice feature so that you can remove the barrel youself and switch barrels. Made me wonder about buying the 16 inch MPX now and SBR later by changing barrel and section of handguard. Mags seem expensive but he found three on sale on SIG webpage. The MPX SBR ran well on cheap 9mm 115FMJ bulk reloads. I want one.

[Default.mp3]

FWIW, Nick Booras over at Side Project has stated that he's been working on a slim M-LOK handguard for the MPX, which will come at the very least in the normal length and the K length, and that 1.375" diameter cans fit under it, though such a can would make most of the M-LOK slots useless due to clearance issues (the 1030s and 0130s would be the only usable ones).

I'm very seriously considering an MPX-K for my PCC; as much as I love H&K, I just don't think the SP5K will come in at a competitive price, and the platform itself is rather dated.

[Josh Runkle]

I'm very seriously considering an MPX-K for my PCC; as much as I love H&K, I just don't think the SP5K will come in at a competitive price, and the platform itself is rather dated.

I don't believe in no-win scenarios. Buy Both! :)

[JSGlock34]

The Atlantic Firearms sale on MKE roller locks broke my resolve. I had wanted to get into the PCC game before 41F took effect...Z-5RS on the way! The sale price basically covers the tax stamp...now to hunt for 922R complaint parts for the SBR build (one aspect that MPX owners doesn't have to deal with).

Atlantic Firearms Z-5RS (http://www.atlanticfirearms.com/component/virtuemart/shipping-rifles/zenith-z-5rs-9mm-pistol-detail.html?Itemid=0)

http://www.atlanticfirearms.com/images/stories/virtuemart/product/zenith%20(1%20of%201).jpg

(Disclaimer: I've no affiliation with Atlantic Firearms or MKE - just sharing a deal.)

[TCinVA]

I like the Sig's ergos, but it's rudely expensive and the magazines are rudely expensive too...and I've heard more than one complaint about guns that don't work.

A buddy of mine runs the gun counter at Colonial Shooting Academy. He has an earlier gen CZ that he's made some modifications to and has done the full SBR route on.

7464

He gave it to me for some trigger time while I was there and I put a couple of hundred rounds through it.

Mods include:

1. Different trigger spring which significantly improves trigger pull
2. Different safety lever which lessens the stabbing unpleasantness of the stock part. There is an AK style lever that works even better than the one he had on the gun

His worked splendidly with everything I fed it. It's a straight blowback gun which he says doesn't give you any problem with gas in the face when run with a can. I didn't play with it suppressed so I can't personally verify that, but I trust the guy 100%.

The gun thumps a little harder than I expected. For best results you really need to be aggressive behind the gun to keep it on a tight target with anything more than a 2 shot string. In full auto I can only imagine it's a real handful due to the blowback design and relatively light weight.

Mags for the gun run about 20 bucks.

Chief appeal is cost...for the cost of a competitor like the Zenith (which I like quite a bit) or the MPX, you can get the CZ, make the aforementioned upgrades, buy the folding stock, and pay the tax stamp...and still have money left over.

[ReverendMeat]

Chief appeal is cost...for the cost of a competitor like the Zenith (which I like quite a bit) or the MPX, you can get the CZ, make the aforementioned upgrades, buy the folding stock, and pay the tax stamp...and still have money left over.

I recall you mentioning some time ago that you were going to pick up one of the Zenith pistols. Did you ever end up doing a write-up or review on it? I have an itch I need to scratch and I've been going back and forth between the Zenith and Brethren (price difference is about $300), would be interested to get your thoughts on yours.

[James_f]

I'm looking hard at the MPX to SBR. But if I went NFA/QC10 and run a Glock mag setup AR I could almost pay for the can with the savings. I see experiences with this platform as either great or bad. Any opinions?

[ranger]

I just bought a SIG MPX Gen 2 pistol from my favorite local gun store. Now to file the NFA form to SBR. My wife said I cannot no longer hang out with the shooting buddy who let me shoot his! She'll change her mind when she gets to shoot it.

[9mm_shooter]

Sig MPX is like a miniature AR in 9x19. I just refuse to get into any more Sigs. I went with CZ for that reason, and my Scorpion EVO sbr has been reliable, both suppressed (AAC Evo9 CQC), and without it as well. It has different controls than the SIG MPX, and is more like an AK in that sense. Trigger group is very AK-like as well - which isn't surprising, since it comes from an ex-iron curtain country. Price point is good too.

Another option, if you want to avoid both CZ and SIG USA, is to look at the Brugger & Thomet APC9. Price is significantly higher though, but you get the best of both worlds: reliability, similar controls to the AR, and compact size.

http://www.thetruthaboutguns.com/2015/10/foghorn/first-impressions-bt-apc9/

[Kennydale]

Shot one at a Range Demo (Texas International Firearms Festival). It is very impressive to me. Just can't afford one !

[TCinVA]

Wilson Combat just entered the fray:

http://wilsoncombat.com/new/rifle-ar9-carbine.asp#.Vytq2DArJaQ

They make them in pistol and carbine format, capable of taking Glock magazines, Beretta 92 magazines, or S&W M&P magazines. Given the typical price point on the MPX I'd be quite tempted to buy one of the WC guns instead of the MPX.

[TCinVA]

I recall you mentioning some time ago that you were going to pick up one of the Zenith pistols. Did you ever end up doing a write-up or review on it? I have an itch I need to scratch and I've been going back and forth between the Zenith and Brethren (price difference is about $300), would be interested to get your thoughts on yours.

So far I quite like mine. I haven't done a whole lot of shooting with it because I haven't found a brace setup that I really like yet. But it's been reliable and accurate enough to reliably clear a plate rack at 50 yards. I've just been too busy/lazy to give it a really proper workout.

[HCM]

What is the difference between the MPX gen 1 and gen 2 ?

Also, What are the differences and compatibility between the Gen 1 and gen 2 mags ?

[Default.mp3]

What is the difference between the MPX gen 1 and gen 2 ?

Also, What are the differences and compatibility between the Gen 1 and gen 2 mags ?

https://www.youtube.com/watch?v=Tp7WmEPyu_k
http://www.realgunreviews.com/sig-mpx-faq-video-analysis/

Long story short, Gen 1s are stuck in 9mm, while Gen 2 will have caliber conversion kits; receivers are interchangeable with lowers (thus Sig's solution of offering Gen 1 owners Gen 2 uppers at Gen 2 caliber conversion kit cost). Gen 1 and Gen 2 mags are interchangeable between both generations, but Sig recommends using like gen mags with like gen guns.

[mrozowjj]

In theory I really like the MPX. I say in theory because one of my chief complaints about blowback 9mm carbines is that the recoil often feels heavier than a 556 rifle thus making my logic circuits go "Similar 556 recoil, less energy what's the point?" so the MPX being a short stroke gas piston appeals to me because the recoil should be almost non-existant which is far more appealing. But at $1800 for the carbine I'm still having a hard time with it. At $1800 part of me wants to get a 9mm Tavor because I like the Tavor a lot and it'd give me a short gun to shoot in USPSA PCC. But the Tavor 9mm is blowback and if I'm going to get a blowback 9mm might as well get a Scorpion for $800 less. This the circle my brain is going in for the last few days.

[Josh Runkle]

I have the carbine version of the MPX. Felt recoil is the same/slightly less than an MP5. I don't get all of these recoil complaints. Are people actually out there shooting them?

[Josh Runkle]

Best solution: buy an MP5, a scorpion, an MPX, GLOCK AR15 carbine, etc...but them all!

[mrozowjj]

I have the carbine version of the MPX. Felt recoil is the same/slightly less than an MP5. I don't get all of these recoil complaints. Are people actually out there shooting them?

I haven't shot a MPX but I've shot a MP5 so that's good to know. I don't know what complaints you're talking about. I was refering to blowback guns.

[KPD]

I got to handle a factory SBR MPX today. It had the new factory optic mounted on it that looks kind of like an Aimpoint. The reticle was more like an eotech though. Supposedly the sight is motion activated. Turns off after twenty minutes of no movement but turns on as soon as it is moved.
Anyway, the carbine appeared to be very well made. Everything locked up solid and worked smoothly. I did not get a chance to fire one. Supposedly SIG is working on integrally suppressed models as well as .40 and .357.
Cost for the 9mm ones I saw were $1200.00 with the sight. That was the non-cop street price.

[James_f]

That sounds like a great deal. I just paid $1150 for a pistol with just irons. Still gotta add a stock, sight and pay for the stamp

[ccmdfd]

Resurrecting an old thread but felt like it belongs here rather than a new one.

What kind of setup/ammo/suppressor combos are people finding work well with the MPX?

I purchased a 6 inch barreled version. When it came in I did not have a fixed barrel spacer for my Eco 9, so I grabbed some Blazer 124gn, went to the range, and sighted in the RDS. I felt like I got good groups at 25 and 50 yards.

Well the fixed spacer came in last week, so I attached the Eco 9, grabbed some American Eagle 147gn to take full advantage of the suppressor and went to the range.
First 3 shots weren't centered, but were a respectable group. After that though, it really opened up and had no good consistency at all. Target looked like a shotgun was taken to it.

I checked both the RDS and can, they are both still nice and tight.

So I'm wondering if I need to give up on the subsonic ammo, try a longer barrel, or something else.

Thanks
cc

[HCM]

Resurrecting an old thread but felt like it belongs here rather than a new one.

What kind of setup/ammo/suppressor combos are people finding work well with the MPX?

I purchased a 6 inch barreled version. When it came in I did not have a fixed barrel spacer for my Eco 9, so I grabbed some Blazer 124gn, went to the range, and sighted in the RDS. I felt like I got good groups at 25 and 50 yards.

Well the fixed spacer came in last week, so I attached the Eco 9, grabbed some American Eagle 147gn to take full advantage of the suppressor and went to the range.
First 3 shots weren't centered, but were a respectable group. After that though, it really opened up and had no good consistency at all. Target looked like a shotgun was taken to it.

I checked both the RDS and can, they are both still nice and tight.

So I'm wondering if I need to give up on the subsonic ammo, try a longer barrel, or something else.

Thanks
cc

AKAIK the make a 4” and an 8” from the factory.

Does your can go under the handguards ?

[ccmdfd]

Yes the can is under the handguards, sticks out around an inch past the handguard.

Thanks

[HCM]

Yes the can is under the handguards, sticks out around an inch past the handguard.

Thanks

Do some searching here in either CZ scorpion or suppressor threads. I recall PF member PaulD had a similar issue.

[ccmdfd]

Looks like he got his problems resolved with going to a 3 lug mount.

So far I can't find a 3 lug adapter for the Eco 9. They are no longer in production.

Slight off topic rant: I now have 2 cans which are out of production and when that happens, spare parts dry up super fast. My Trident 9 was top of the line when I purchased it and within 2 years I couldn't find any parts. Next time I purchase a can I'm going to buy every single adapter they make for it right away.
Anyway, back on topic.

Thanks for the help.

cc

[ranger]

I bought a SIG MPX 9mm pistol (8 inch) and went the SBR route. Recently got an AAC Tirant 9mm suppressor. Bought a 4.5 inch barrel and most of the suppressor is inside the OEM handguard. Mounted a C-More red dot (the original style popular in USPSA Open). In fact, I just got home from the range and I ran about 200 rounds of my 124FMJ reloads through the combination. I really enjoy it and I have had not any issues with the MPX - please note that my MPX is "stock" except for the 8 inch barrel replaced by a 4.5 inch barrel. It is really neat with the 147 reloads.

[GJM]

Competition model MPX:

http://www.recoilweb.com/watch-recoiltv-nra-2018-sig-sauer-competition-ready-mpx-136997.html

[GJM]

And, here it is:

https://www.thefirearmblog.com/blog/2018/11/27/upgraded-mpx-pcc/

[JFK]

I have been pretty happy with mine. I use it for shooting the games. It is the 8" SBR. It really cycles fast and I think the 8" is perfect balance between having a rifle and a short barrel to move around.

I have never shot is suppressed though, and I don't have a very high round count through this, maybe 4000 rounds. So long term I am not sure, but so far the only issue I had was with the extended base magazines. The +10 spring that allows the 30 round mag to be 40 rounds is a little too + and it would push up the rounds too hard near the middle of the magazine, causing double feeds. Exercising the spring worked this problem out. Not really a gun issue, but an aftermarket issue.

It really is like shooting a .22. It cycles so fast on the cycle people have asked it it was auto, or had a binary trigger. (it does not)


32827

32826

[4gallonbucket]

I have been pretty happy with mine. I use it for shooting the games. It is the 8" SBR. It really cycles fast and I think the 8" is perfect balance between having a rifle and a short barrel to move around.

I have never shot is suppressed though, and I don't have a very high round count through this, maybe 4000 rounds. So long term I am not sure, but so far the only issue I had was with the extended base magazines. The +10 spring that allows the 30 round mag to be 40 rounds is a little too + and it would push up the rounds too hard near the middle of the magazine, causing double feeds. Exercising the spring worked this problem out. Not really a gun issue, but an aftermarket issue.

It really is like shooting a .22. It cycles so fast on the cycle people have asked it it was auto, or had a binary trigger. (it does not)


32827

32826

Looks great. I have to ask though, why do you have two dots on it?

[JFK]

For shooting games it makes it very fast reaching around corners or shooting low targets up close.

Try this with your AR....

Shoulder the weapon normally straight on. Then try to lean around a corner and still see the dot. With the 45 degree offset I can still have a natural shoulder while leaning around a corner.

It also works on the lay down targets. Think of a target 3 -4 feet in front of you on the ground at an angel. Hard to shoulder the weapon and get a sight picture. Rotate it 45 and it is much easier.

Gamers gonna game....

[JFK]

Looks great. I have to ask though, why do you have two dots on it?

I mean, because I am Operator AF and one is none and two is a ham sandwich or something like that....

[ranger]

MPX trigger update. I was not happy with my factory SIG MPX trigger - went bang every time but trigger pull was awful. Replaced with a traditional "AR" trigger but that "AR" trigger in my MPX "slapped" my finger every trigger pull. Kept reading the web and looking for a trigger that would survive on MPX. Found the KEARMS SLT-1 trigger which is marketed as being MPX compatible. Had it for about 60+ days now - it has survived so far through about 400 rounds with no more trigger finger "sting". That was the one weak point so far in my MPX so hope it is a long term solution.

[Sensei]

Here is the latest iteration of the MPX: the Copperhead

https://www.sigsauer.com/press-releases/sig-sauer-releases-the-ultra-compact-mpx-copperhead/

I have absolutely no use for a 3.5” barrel 9mm PCC.

[Hambo]

For shooting games it makes it very fast reaching around corners or shooting low targets up close.

Try this with your AR....

Shoulder the weapon normally straight on. Then try to lean around a corner and still see the dot. With the 45 degree offset I can still have a natural shoulder while leaning around a corner.

It also works on the lay down targets. Think of a target 3 -4 feet in front of you on the ground at an angel. Hard to shoulder the weapon and get a sight picture. Rotate it 45 and it is much easier.

Gamers gonna game....

Right, but don't you really need three to shoot R and L corners? You be Operator and Gamer AF. Build the mount yourself, get Operator Zero to YouTube it, and you could be rich AF.

[GJM]

I am waiting on form one paperwork to clear on a MPX Competition model so I can run an eight inch upper on it for JFK style gaming.

[Super77]

So what's the consensus on the MPX? Are these FMC? Any reliability/longevity issues people are noticing on the newer models?

[JSGlock34]

Older thread, but wanted to see what the current state of the MPX is. Considering one for PCC, probably the competition model.

[GJM]

Older thread, but wanted to see what the current state of the MPX is. Considering one for PCC, probably the competition model.

Delightful to shoot, especially with factory ammo as the gas system makes for a soft shooting PCC. They all break, it is just a matter of when.

[Eyesquared]

It seems that the best PCC option for competition is still the AR 9mm based setup. Max Leograndis has put some info out on his Instagram on good components and he seems responsive to questions. I know a guy who set one up per Max's advice and he is very satisfied with the performance (he switched from a JP 9mm)

[nalesq]

Delightful to shoot, especially with factory ammo as the gas system makes for a soft shooting PCC. They all break, it is just a matter of when.

Are the Gen 2 MPXes any substantive improvement over the Gen 1 models, particular with respect to durability issues?


Sent from my iPhone using Tapatalk Pro

[GJM]

Are the Gen 2 MPXes any substantive improvement over the Gen 1 models, particular with respect to durability issues?


Sent from my iPhone using Tapatalk Pro

I had early ones, and also the latest competition model, which is either Gen 2 or 3. The competition model is improved, but they still break. Was just speaking with a local shooter whose MPX competition model was flawless until he got to the PCC Nationals, where lack of reliability ruined his match. The MPX is probably a great gun for Steel Challenge, since if it goes down, it can be your throw away run. :p

As I have said before, if soldiers went to war with either a MPX or blow back AR9, it would be ugly, and I am talking about lack of reliability not terminal ballistics.

[GJM]

It seems that the best PCC option for competition is still the AR 9mm based setup. Max Leograndis has put some info out on his Instagram on good components and he seems responsive to questions. I know a guy who set one up per Max's advice and he is very satisfied with the performance (he switched from a JP 9mm)

Of course, last I heard, Max was carrying a spare BCG on his competition belt.

[JSGlock34]

Delightful to shoot, especially with factory ammo as the gas system makes for a soft shooting PCC. They all break, it is just a matter of when.

What usually goes down? Are parts difficult to source?

[GJM]

What usually goes down? Are parts difficult to source?

All sorts of things around the firing pin, firing pin string, extractor and gas system. I am not even counting triggers which are tough in the MPX and blow back AR9 guns.

Sig can be tough on parts. When I broke a firing pin spring before Area 2 a few years ago, they only had two springs in stock, and sent me them to the wrong place, forcing me to use my second MPX as a spare parts gun and hope I didn’t break another spring. ILWT has carried MPX parts, as a source other than Sig. An issue with Sig is they often don’t want to send parts, they want you to return the whole gun.

If you are a serious competitor, I think you want three MPX guns, so can practice with one, compete with another and have a third for back up or parts.

[fatdog]

If you are a serious competitor, I think you want three MPX guns, so can practice with one, compete with another and have a third for back up or parts.

Reminds me of the CAS mantra on Win'97's and their reputation for breaking, if you run one of those you need three, one to start the match, one to finish the match, and one that is already away being fixed.

I have been tempted about getting one of these, but this whole report is not encouraging. I have enough stuff that breaks routinely. All evidence including your experience and the competitors who excel with it says it is one of the best shooting of the PCC platforms.

[JSGlock34]

All sorts of things around the firing pin, firing pin string, extractor and gas system. I am not even counting triggers which are tough in the MPX and blow back AR9 guns.

Thanks - that's interesting. Is it something particular to the design or 9mm gas system that's causing these problems? It doesn't seem like the MCX suffers from the same issues (not an apples to apples comparison but some shared design history).

[GJM]

Thanks - that's interesting. Is it something particular to the design or 9mm gas system that's causing these problems? It doesn't seem like the MCX suffers from the same issues (not an apples to apples comparison but some shared design history).

I asked the exact same question and was told that the MCX does not have a gas system issue because the rifle powder burns so clean, and the MPX has gas system issues because the pistol cartridges are quite dirty.

[HCM]

Sunday JM Campbell and I got to shoot on a friends property and I took the opportunity to try a variety of loads in my 8' gen2 MPX before detail stripping and cleaning the gas piston. Each was a 25 round magazine:


1) Blazer 115 grain FMJ - multiple malfunctions
2) Speer Gold Dot 124 grain +P - No malfunctions
3) Speer Lawman 115 Grain +P FMJ - No malfunctions
4) Federal Synthtech 150 grain Coated Truncated Cone - Multiple malfunctions
5) Winchester Ranger 147 grain bonded JHP - Multiple malfunctions
6) Federal American Eagle 124 grain FMJ - No malfunctions
7) Federal White box (LE Contract) 147 grain TMJ (truncated cone) No malfunctions
8) Magtech 115 grain FMJ - No malfunctions

It seemed the hotter the ammo the better it ran and it seemed to work best with the +P stuff.

Anyone else had similar experiences with their MPX ?

I've got a few thousand rounds on the gun (Mostly Magtech 115) so I'll try and repeat this after cleaning the gas piston and compare results.

Clusterfrack didn't you mention using anti-seize of the piston in one of the PDW threads ?

My agency has adopted the MPX and just issued a 9 page cleaning and maintenance procedure which includes cleaning the gas piston.

Another thought:

Has anyone seen differences in reliability between the 4', 8' and 16' barreled variants ?

I recently saw a MAC video (I know) about issues he had with a new MPX and the how using an MI taper adapter effected accuracy. He tried to buy a taper adapter from SIG but they stopped selling them and SIG CS could not tell him why. He speculated maybe SIG knew about the taper adapters causing issues and quietly discontinued them. This got me thinking about SIG discontinuing the 8' MPXs. In the recent TFB interview with a SIG executive, they asked why the 8' was discontinued. The reply was that " SBRs dont sell" which was curious as I'm sure most of the 8' MPX SIG sold were brace pistols. I'm curious as to whether SIG discontinued the 8" because the 4" guns ran better ?

If work hadn't adopted these I'm pretty sure I would have traded it in on an APC PRO by now.....

[Clusterfrack]

It seemed the hotter the ammo the better it ran and it seemed to work best with the +P stuff.

Anyone else had similar experiences with their MPX ?
Clusterfrack didn't you mention using anti-seize of the piston in one of the PDW threads ?


It must have been someone else using anti-seize. GJM? I don’t have an MPX, but my buddy has a troublesome one that does not work well with anything below 140 power factor.

[ranger]

I use antiseize on my MPX piston - I probably shared that on a post. Still no issues with mine using a variety of 115-124 FMJs. Mostly 115 FMJs over 5.1 WSF. Mine is a Gen 2 8 inch pistol (now SBR) and I also have an aftermarket 4.5 inch barrel.

[olstyn]

I asked the exact same question and was told that the MCX does not have a gas system issue because the rifle powder burns so clean, and the MPX has gas system issues because the pistol cartridges are quite dirty.


Sunday JM Campbell and I got to shoot on a friends property and I took the opportunity to try a variety of loads in my 8' gen2 MPX before detail stripping and cleaning the gas piston. Each was a 25 round magazine:


1) Blazer 115 grain FMJ - multiple malfunctions
2) Speer Gold Dot 124 grain +P - No malfunctions
3) Speer Lawman 115 Grain +P FMJ - No malfunctions
4) Federal Synthtech 150 grain Coated Truncated Cone - Multiple malfunctions
5) Winchester Ranger 147 grain bonded JHP - Multiple malfunctions
6) Federal American Eagle 124 grain FMJ - No malfunctions
7) Federal White box (LE Contract) 147 grain TMJ (truncated cone) No malfunctions
8) Magtech 115 grain FMJ - No malfunctions

It seemed the hotter the ammo the better it ran and it seemed to work best with the +P stuff.

So then is the answer for competition 95 grain JHP bullets intended for .380 loaded into 9mm cases over enough CFE-Pistol to kick them along at 1400 FPS? (133 PF) Should be more than plenty of gas to run the system, loaded that hot CFE-P should burn pretty clean, and the MPX being gas-operated will tame down the recoil, plus it'll be way louder than any other PCC ever, so you won't have problems with shot timers picking up your shots. Win-win-win-win?

[HCM]

So then is the answer for competition 95 grain JHP bullets intended for .380 loaded into 9mm cases over enough CFE-Pistol to kick them along at 1400 FPS? (133 PF) Should be more than plenty of gas to run the system, loaded that hot CFE-P should burn pretty clean, and the MPX being gas-operated will tame down the recoil, plus it'll be way louder than any other PCC ever, so you won't have problems with shot timers picking up your shots. Win-win-win-win?

They seem to run fine on +P Gold Dot 124 grain and the Speer 115 +P. A Nato ball equivalent should do the trick.

Or SIG could release the 40 S&W and .357 SIG conversion kits they promised back in the day.

[HCM]

It must have been someone else using anti-seize. GJM? I don’t have an MPX, but my buddy has a troublesome one that does not work well with anything below 140 power factor.


I use antiseize on my MPX piston - I probably shared that on a post. Still no issues with mine using a variety of 115-124 FMJs. Mostly 115 FMJs over 5.1 WSF. Mine is a Gen 2 8 inch pistol (now SBR) and I also have an aftermarket 4.5 inch barrel.

ranger Thanks. Is it the ILWT barrel ? Also copper or silver/aluminum anti-seize ?

[Caballoflaco]

In 120 + years of automatically repeating firearm development there has yet to be a successful pistol caliber smg or carbine that uses a gas-driven piston operating system. I have my doubts that SIG is going to be the company that makes that happen,.

[ranger]

ranger Thanks. Is it the ILWT barrel ? Also copper or silver/aluminum anti-seize ?

I use the OEM 8 inch 95% of the time. The 4.5 inch barrel is the ILWT and I use it with an AAC TiRant 9 with the OEM handguard.

I use the copper anti-seize in a tube. Put some on the piston after cleaning as I reassemble.

[HCM]

I use the OEM 8 inch 95% of the time. The 4.5 inch barrel is the ILWT and I use it with an AAC TiRant 9 with the OEM handguard.

I use the copper anti-seize in a tube. Put some on the piston after cleaning as I reassemble.

That stuff gets EVERYWHERE but I may have to try some.

[ranger]

That stuff gets EVERYWHERE but I may have to try some.

Yes, I use a Q tip to minimize issues.

[JCN]

Sunday JM Campbell and I got to shoot on a friends property and I took the opportunity to try a variety of loads in my 8' gen2 MPX before detail stripping and cleaning the gas piston. Each was a 25 round magazine:


1) Blazer 115 grain FMJ - multiple malfunctions
2) Speer Gold Dot 124 grain +P - No malfunctions
3) Speer Lawman 115 Grain +P FMJ - No malfunctions
4) Federal Synthtech 150 grain Coated Truncated Cone - Multiple malfunctions
5) Winchester Ranger 147 grain bonded JHP - Multiple malfunctions
6) Federal American Eagle 124 grain FMJ - No malfunctions
7) Federal White box (LE Contract) 147 grain TMJ (truncated cone) No malfunctions
8) Magtech 115 grain FMJ - No malfunctions

It seemed the hotter the ammo the better it ran and it seemed to work best with the +P stuff.

Anyone else had similar experiences with their MPX ?

I've got a few thousand rounds on the gun (Mostly Magtech 115) so I'll try and repeat this after cleaning the gas piston and compare results.

Clusterfrack didn't you mention using anti-seize of the piston in one of the PDW threads ?

My agency has adopted the MPX and just issued a 9 page cleaning and maintenance procedure which includes cleaning the gas piston.

Another thought:

Has anyone seen differences in reliability between the 4', 8' and 16' barreled variants ?

I recently saw a MAC video (I know) about issues he had with a new MPX and the how using an MI taper adapter effected accuracy. He tried to buy a taper adapter from SIG but they stopped selling them and SIG CS could not tell him why. He speculated maybe SIG knew about the taper adapters causing issues and quietly discontinued them. This got me thinking about SIG discontinuing the 8' MPXs. In the recent TFB interview with a SIG executive, they asked why the 8' was discontinued. The reply was that " SBRs dont sell" which was curious as I'm sure most of the 8' MPX SIG sold were brace pistols. I'm curious as to whether SIG discontinued the 8" because the 4" guns ran better ?

If work hadn't adopted these I'm pretty sure I would have traded it in on an APC PRO by now.....


Bumping this up for updated thoughts on weak gamer ammo. I know a lot of factory springs can be too stiff with gamer
ammo, ordered an 8” and looking forward to learning it.

[JCN]

Like every time I learn a new platform there are idiosyncrasies…

Doh Sig for making a 13.5LH thread! WTF man.

The only thing I have in that is:

81951

Which might be enough back pressure to help cycle gamer 9mm?

[HCM]

Bumping this up for updated thoughts on weak gamer ammo. I know a lot of factory springs can be too stiff with gamer
ammo, ordered an 8” and looking forward to learning it.

Check out In Lead We Trust for options. Still haven’t cleaned that gas system.

The newer 4.5” guns don’t seem to be as ammo sensitive and my older /early Gen 2.

The mag tech 115 is not super hot but seems to run fine.

It seemed like it didn’t like 147-150 grain or flat nose profiles.

[JCN]

Check out In Lead We Trust for options. Still haven’t cleaned that gas system.

The newer 4.5” guns don’t seem to be as ammo sensitive and my older /early Gen 2.

The mag tech 115 is not super hot but seems to run fine.

Thank you! I also found this Enos thread

https://forums.brianenos.com/topic/253256-sig-mpx-failure-to-eject/page/2/

And bought some of the BCM O-ring and spring for extractor

[HCM]

Thank you! I also found this Enos thread

https://forums.brianenos.com/topic/253256-sig-mpx-failure-to-eject/page/2/

And bought some of the BCM O-ring and spring for extractor

If you were buying a new production gun you may not need any of that.

Sigg does not acknowledge a GEN three MPX but in my experience the latest 4.5 inch and 16 inch guns which come from the factory with MLOK hand guards straight Timney trigger run noticeably better than the older Kimon handguard era GEN 2 guns.

I’ve actually thought about cashing out of this older gun and picking up a new 8 inch LEO model. Seguin is definitely one of those companies that shows a higher standard of care in terms of parts assembly and overall QC for their IOP line products.

[JCN]

If you were buying a new production gun you may not need any of that.

Sigg does not acknowledge a GEN three MPX but in my experience the latest 4.5 inch and 16 inch guns which come from the factory with MLOK hand guards straight Timney trigger run noticeably better than the older Kimon handguard era GEN 2 guns.

I’ve actually thought about cashing out of this older gun and picking up a new 8 inch LEO model. Seguin is definitely one of those companies that shows a higher standard of care in terms of parts assembly and overall QC for their IOP line products.

I can’t tell but I was just figuring if it was an 8” it probably wouldn’t have all the current upgrades?

81953

Mlok plus curved trigger?

[JCN]

ILWT: tuning spring pack (maybe +20% for Syntech 150)
BCM: extractor kit
TTI: magwell, +10 basepads, springs and compensator
MGW: Timney trigger
Osage County: 30 round magazines

This will mainly be for recreational gaming.

[GJM]

I have two of the latest MPX 16 inch carbines. Many of my friends have them for USPSA PCC. The latest Gen work better, and everyone loves how they shoot, right up until they fail and ruin your match. It is not a question of "if," it is a question of "when." I would never rely on an MPX to save my life. Something about 9mm carbines generally, and pistol powder and that gas system.

I had a horrendous CS experience with ILWT, that would make me unwilling to depend upon them.

The new JP looks interesting in that it has AR ergos with the guts of an MP5.

[CleverNickname]

Like every time I learn a new platform there are idiosyncrasies…

Doh Sig for making a 13.5LH thread! WTF man.

The only thing I have in that is:

81951

Which might be enough back pressure to help cycle gamer 9mm?

"Gamer 9mm"? If you're planning on using a silencer in USPSA PCC, it's not allowed as per appendix D8, section 14.

Also, 13.5 LH is a pretty common thread for 9mm in Europe.

[JCN]

"Gamer 9mm"? If you're planning on using a silencer in USPSA PCC, it's not allowed as per appendix D8, section 14.

Also, 13.5 LH is a pretty common thread for 9mm in Europe.

Oh thanks! I’m a long gun noob so I appreciate the help!

Gamer ammo is easier to say than Syntech 150.

Read the PCC appendix and looks like I need a stock even if it’s an SBR, too.

So much to learn!

[HCM]

I can’t tell but I was just figuring if it was an 8” it probably wouldn’t have all the current upgrades?

81953

Mlok plus curved trigger?

Well, new style brace and Mlok handguard is a positive sign.

Re: Gaming both USPSA and IDPA PCC rules exclude braces you need either a 16" gun or an SBR with actual stocks.

I was looking to buy a 16" MPX but stumbled on a used Gen 1 JP https://pistol-forum.com/showthread.php?32301-What-did-you-shoot-today&p=1299271&viewfull=1#post1299271

IME the MPX is a love it or hate it thing with PCC folks.

As a cheap practice gun for a rattler, it should be fine. The nice thing about modularity is you can mimic your cane break with a longer handguard and suppressor.

We are running both the K (4.5") and factory Cane Break SMGs at work.

[HeavyDuty]

I’m sorry to hear that the MPX has reliability and durability issues. I keep looking at the K and Copperhead variants up at the Pro Shop, but already having a SBRed Scorpion has been holding me back. But it’s been close more than a few times - they are very appealing.

[GJM]

IME the MPX is a love it or hate it thing with PCC folks.
.

Yep, love it right up until it stops running, and then hate it.

I know a top PCC guy, who at major matches cleans the gas system every night, and that necessitates removing the barrel.

[JCN]

HCM
GJM

I know you guys are right and I suspect eventually I’ll get one of the delayed roller JPs and go full gamer.

But I’m trying (not very successfully) to resist.

I’m trying to ease my brain into long guns with some fantasy application of my home defense stuff for training.

It’s kind of like running a carry gun at a game… eventually the gamer in me wants to game. But I’m trying to resist…

If there’s a huge performance difference in recoil impulse and shootability between the 9mm X95 and MPX then I’ll probably cave and just get a JP.

I know resistance is futile but I’m trying….

[Clusterfrack]

A few thoughts: I don’t shoot PCC, and don’t own one for at least two reasons. I’ll set aside my opinions about PCC as a legitimate USPSA division, and the level of difficulty of PCC classification for a different thread.

1) A reliable gamer PCC is rare, and while the MPX fails regularly, so do all PCCs I’ve seen. Even PCC GMs at Area matches don’t look surprised when their guns fail.

2. (Possibly controversial Timmy reason): At a certain level of skill with a handgun, especially with RDS, a semi-auto PCC is not an advantage anymore.

[GJM]

The advantage of the MPX is you can fire full power factory ammo with a modest recoil impulse. To get that with a blow back, you need to load down your ammo. Shooting Lawman in a blow back feels like successive explosions going off.

If I wanted a self defense 9mm, it would most likely be a MP5 equivalent.

[Clusterfrack]

The advantage of the MPX is you can fire full power factory ammo with a modest recoil impulse. To get that with a blow back, you need to load down your ammo. Shooting Lawman in a blow back feels like successive explosions going off.

If I wanted a self defense 9mm, it would most likely be a MP5 equivalent.

But why bother when rifle caliber pistols or SBRs work better in every way?

[GJM]

But why bother when rifle caliber pistols or SBRs work better in every way?

No argument here -- I use a Rattler, 1301/M2, or 5.56 AR carbine. The difference between a service pistol with a dot and a PCC isn't enough for me to deal with the size and considerations of a PCC for defense.

A pistol caliber may be attractive for people that are not skilled with a handgun, or are worried about concussion.

[HCM]

But why bother when rifle caliber pistols or SBRs work better in every way?

For me the reason I bought my first 9 mm A.R., a colt was the primary range I had access to only allowed pistol calibers.

Two other advantages are cheap ammo and the ability to shoot steel targets a closer ranges.

For real world applications the only real advantage is size and maybe cost.

The only micro gun I’ve seen which I’d consider for serious use is the rattler and it is rather pricey.

I won’t be giving up my 11.5 inch 556 at work for an MPX. If I worked a different type of assignment and needed a lower profile long gun the 4.5 inch as a bad gun might be better than a pistol but it’s a niche application.

[nalesq]

Yep, love it right up until it stops running, and then hate it.

I know a top PCC guy, who at major matches cleans the gas system every night, and that necessitates removing the barrel.

Does removing and reattaching the barrel, especially so often, mess with the zero?


Sent from my iPhone using Tapatalk Pro

[HCM]

Does removing and reattaching the barrel, especially so often, mess with the zero?


Sent from my iPhone using Tapatalk Pro

It shouldn't. You only remove the lower portion of the rail and the barrel has to be properly torqued when reinstalled.

[Caballoflaco]

I wish it wasn’t made by such a small company, because the CMMG delayed radial blowback gun is one of the most interesting developments in pistol caliber this century. Have any of you gamer guys seen people running those uppers in USPSA?

[GJM]

Does removing and reattaching the barrel, especially so often, mess with the zero?


Sent from my iPhone using Tapatalk Pro

Not noticeably with a 25 yard zero, but if it were a 100-500 yard rifle, I would want to rezero.

Here is mine.

81982

[CleverNickname]

I wish it wasn’t made by such a small company, because the CMMG delayed radial blowback gun is one of the most interesting developments in pistol caliber this century. Have any of you gamer guys seen people running those uppers in USPSA?
My USPSA PCC is a CMMG RDB. I have maybe 1k rounds through it, about half of that shooting USPSA and the other half doing recreational full-auto on my M16. Supposedly the bolt is the weak point, so I bought a spare but haven't had to use it. I haven't run across anyone else shooting one.

[mrozowjj]

But why bother when rifle caliber pistols or SBRs work better in every way?

Agreed.

I have tried to find a niche for the PCC but I just can't. I've tried a bunch and they are kind of fun but ultimately they sit in my safe and I just ask myself "Why do I have that?" because there is no situation I can think of where a 9mm gun like a 5" MPX or B&T APC or SP5K or Scorpion or whatever is better than a 8-11" gun in 5.56mm or .300 blk. Ballistics of a 5.56 gun with a barrel that short aren't great, you loose a lot of range and energy but it still has more range and energy than a 9mm.

[JCN]

I’m kind of a noob to long guns and PCC.

But I don’t know what I don’t know.

So I’ll keep running the X95 until I test the MPX.

I also just put in a preorder for a JP5. The way I figure, the JP is like the Shadow 2. The next iteration of the previous successful proven platform so if I’m going to learn what I don’t currently know, I have to put in the time and money to get a firsthand education. Which is what I usually wind up doing.

The builds for those can be 6 months out so this is a good time to order.

[Sensei]

I thoroughly enjoy mine. Much less concussion and recoil than my Rattler.

82055

[CleverNickname]

I thoroughly enjoy mine. Much less concussion and recoil than my Rattler.

82055

Someone explain to me the attraction of the SIG dual-rod collapsible stock, other than some nostalgia for the old HK collapsible stocks that are sort of similar. The SIG collapsing/folding stock has a shorter OAL when folded, and has a better cheek weld than the dual-rod collapsible.

[Caballoflaco]

Someone explain to me the attraction of the SIG dual-rod collapsible stock, other than some nostalgia for the old HK collapsible stocks that are sort of similar. The SIG collapsing/folding stock has a shorter OAL when folded, and has a better cheek weld than the dual-rod collapsible.

I don’t have one, but have spent 15 years or so with side folding Ak’s and some time with an AR with Law Folder. The advantages I see are they add less width to the gun when collapsed, and you need less space to deploy the stock. I can understand why it’s still an option some folks want.

[JCN]

I ordered a 16" MPX competition model while I wait the months for the JP5.
So that way I can compare the X95 (blowback) to the 8" MPX (arrives Monday) to the 16".

If the 8" is more "fun" (whatever that means) for theoretical gaming use then I'll SBR it.

If the 16" is awesome but maintenance heavy (I do own a large ultrasonic cleaner), then I'll just keep one (or two) as ultra low round count match guns until the JP5 comes in.

[DMCutter]

I have a gen 2 8" that I got going on 3 years ago (I think). I don't keep count of rounds but I know I've run at least 1000 through it, 115 and 124 grain range fodder, HST of various weights, and 147 S&B 147 subsonic most recently. It shoots a ragged hole at 25 yards suppressed or unsuppressed and shoots better at 50 yards than my eyes are capable of with a 503c and 3x magnifier. I don't recall that I've ever had a single malfunction of any description despite not being at all vigilant with respect to cleaning. I put in a Hiperfire MPX specific trigger, Radian charging handle, and ASR flash hider but it's otherwise stock. Other than being over gassed and making me cry when I shoot rapid fire with a can, it's the most amusing gut to shoot that I own. What are the typical failure modes, since common wisdom is that failure is "when, not if"?

[GJM]

I have a gen 2 8" that I got going on 3 years ago (I think). I don't keep count of rounds but I know I've run at least 1000 through it, 115 and 124 grain range fodder, HST of various weights, and 147 S&B 147 subsonic most recently. It shoots a ragged hole at 25 yards suppressed or unsuppressed and shoots better at 50 yards than my eyes are capable of with a 503c and 3x magnifier. I don't recall that I've ever had a single malfunction of any description despite not being at all vigilant with respect to cleaning. I put in a Hiperfire MPX specific trigger, Radian charging handle, and ASR flash hider but it's otherwise stock. Other than being over gassed and making me cry when I shoot rapid fire with a can, it's the most amusing gut to shoot that I own. What are the typical failure modes, since common wisdom is that failure is "when, not if"?

More than 1,000 rounds for sure. Besides the gas system, I have had broken firing pin springs (Sig changed the design of the firing pin and spring several times). Others have reported issues with the extractor and spring. I broke a trigger, but that isn't a MPX specific issue.

ILWT sells a spare parts kit, but you deal with that guy knowing it may be unsatisfactory. The contents of that kit provides clues as to what breaks.

[Dr_Nimslow]

I've got an MPX-K that I SBR'd, and then tried to shoot suppressed. It's a fun little gun, and it certainly looks cool. And we all know thats what's really important.

I've never been able to get acceptable accuracy out of the factory barrel suppressed. With the birdcage flash hider it was around 2" at 25 yards, Not bad. When I installed a Tri-lug adaptor, with just the adaptor on the muzzle, the groups opened up to 7-8"+ at 25 yards. I tried two different trips-lug's, including ILWT's MPX specific one. They both had similar results.

With my CGS Kraken on a direct thread adaptor and fixed spacer, about the same.

I eventually picked up an ILWT barrel, with the machined Tri-lug. It's settled in around 2" at 25. But my gun OCD kicked in and since the ILWT barrel has the old style gas block, I'm curious if it will suffer from the hydro-lock issues if it gets wet. One of these days I'll have to go all MAC on it and see.

Still one of the coolest looking PCC's around.

http://i.imgur.com/qsfyakB.jpg (https://imgur.com/qsfyakB)

[Sensei]

Someone explain to me the attraction of the SIG dual-rod collapsible stock, other than some nostalgia for the old HK collapsible stocks that are sort of similar. The SIG collapsing/folding stock has a shorter OAL when folded, and has a better cheek weld than the dual-rod collapsible.

I have all of the MCX/MPX stock permutations and multiple copies of the MCX/MPX. I vastly prefer the folding stock variations on the MCX for the superior cheek weld with a higher recoil rifle. The major advantage of the dual rod collapsing stock is that it’s a bit faster and easier to deploy/stow in a vehicle or confined space. It also has a more adjustable length for when wearing armor. The folding stock can be a bit stiff.

[CleverNickname]

I have all of the MCX/MPX stock permutations and multiple copies of the MCX/MPX. I vastly prefer the folding stock variations on the MCX for the superior cheek weld with a higher recoil rifle. The major advantage of the dual rod collapsing stock is that it’s a bit faster and easier to deploy/stow in a vehicle or confined space. It also has a more adjustable length for when wearing armor. The folding stock can be a bit stiff.
Ah ok that makes sense. I've not actually used the dual-rod collapsible stock on an MCX myself, because all my short MCXes are really just SBRed AR15's with MCX conversion kits on them, and the receiver extension ring on the AR15 lower interrupts the slot on the MCX upper for the rods on the dual-rod collapsible stock, preventing its use.

[GJM]

JP5:

https://www.gunsamerica.com/digest/is-the-jp-enterprises-jp5-an-mp5-killer-deep-dive-part-1/

[fatdog]

.. CMMG delayed radial blowback gun ...Have any of you gamer guys seen people running those uppers in USPSA?

Yes, at least two I know of locally. One of them told me about a bolt failure of some sort (cam pin broke?) but they are definitely softer shooting than my PSA pure blowback gun, I got to try one.

[jbrimlow]

I have a gen 2 8" that I got going on 3 years ago (I think). I don't keep count of rounds but I know I've run at least 1000 through it, 115 and 124 grain range fodder, HST of various weights, and 147 S&B 147 subsonic most recently. It shoots a ragged hole at 25 yards suppressed or unsuppressed and shoots better at 50 yards than my eyes are capable of with a 503c and 3x magnifier. I don't recall that I've ever had a single malfunction of any description despite not being at all vigilant with respect to cleaning. I put in a Hiperfire MPX specific trigger, Radian charging handle, and ASR flash hider but it's otherwise stock. Other than being over gassed and making me cry when I shoot rapid fire with a can, it's the most amusing gut to shoot that I own. What are the typical failure modes, since common wisdom is that failure is "when, not if"?

I think (but haven't done any kind of study on this) that some of the MPX problems lie with ammo, and people not understanding the MPX. For Prod/CO guns, or blowback PCCs, a lighter powder charge is going to shoot softer. Putting this super soft ammo in the MPX is not the best idea. The MPX is gas operated. It needs gas to run. It likes more gas. More gas gives you more of an operating margin. In that respect, it's more like an open gun. Of course, SIG hasn't helped anything with their perpetual rolling changes.

Things I would keep an eye on are the extractor parts (have spares of that spring/o-ring) and keep the piston/gas expansion chamber clean. Oh, and oil the carrier.

[JCN]

I’m sure it’s available in the thread but in case anyone comes across it:

ILWT color coding of springs:
White +20%
Blue -13%
Red -25%
No paint +0%

I’m sure that I’m reinventing the wheel, but I heard possibly +20% for the 150 Syntech but I’m going to break the guns in with Lawman for a while first. I think Thursday might be the day.

[HeavyDuty]

I stopped at my local FFL yesterday to ship out a gun and handled his personal MPX with telescoping stock and Omega 9K. Hmmm…

[GJM]

I shot Lawman 147 and later American Eagle 115, when I competed with the MPX.

[abu fitna]

Someone explain to me the attraction of the SIG dual-rod collapsible stock, other than some nostalgia for the old HK collapsible stocks that are sort of similar. The SIG collapsing/folding stock has a shorter OAL when folded, and has a better cheek weld than the dual-rod collapsible.

The old HK style stocks are not just nostalgia.
Less to snag when deploying from bag, slimmer profile when concealing with clothing, easier to extend in vehicle. Having used both overseas on MP5A3 and MP5K with side folding setup; there are definite advantages to the former.
I don't mount a stock with the MPX-K in pistol form in normal life, as its easy enough to run with the old push-pull sling method (as we had our MPKs often setup as well). But not doing the old job, so its just a bag gun for places and times when the full carbine bag is a bit too big.

[JCN]

Gotta say this a cool little gun.

82355

16” competition version comes in on Thursday.

Haven’t had a chance to shoot it yet.

[JCN]

82372

Gemtech Aurora II suppressor.

Very cool. I love reduced height over bore and I can get a no-riser 507c to work…

[CleverNickname]

Gemtech Aurora II suppressor.


Why? I have a similar can (Thompson Machine Operative B) and while it's a fun toy for shooting from a handgun, a tiny can with wipes seems sort of underwhelming for a carbine.

[JCN]

Why? I have a similar can (Thompson Machine Operative B) and while it's a fun toy for shooting from a handgun, a tiny can with wipes seems sort of underwhelming for a carbine.

Couple reasons:


https://youtu.be/0A5vMoIHcc0

1. It’s the only LH13.5 threaded anything I own (it’s dual threaded on both ends).
2. I didn’t want to blast my fingers by getting too close to the muzzle.
3. I’m breaking in the gun that is gas driven so I’m trying to increase gas pressure and this is an easy way to do that.
4. It’s only 9mm and I could see using it as a partial mitigation device without having to go full hearing safe.

I bought some thread adapters so I can use any of my traditional 9mm suppressors on it.

That was with the factory 8 pound trigger. The comps haven’t been delivered yet.

[JCN]

Here’s comparison to a 16” with a compensator, same ammo.


https://youtu.be/N4KCPux7bTg

[JCN]

CleverNickname

Also, it may be relevant that the wipes on my can are pretty much blown out so I don’t use it as much suppression.

I used it for shooting 22LR pistols out of fixed barrel handgun so as not to upset the weight or balance of the gun and to not annoy the neighbors as much. Not for “hearing safeness.”

Same thing for this. If I were going to use it for home defense I might actually choose to go with a not so effective suppressor to prevent adding a lot of length. I have a professional grade $3k sound dB meter and I think I tested it with wipes blown out and it’s better than nothing (but obviously louder than 140dB). I can try and dig up the data.

I don’t like wipes because they don’t play nice with hollow points. These have a nice hole blown out of the center already, lol.

[JCN]

Set up the guns reasonably the way I want them I think…

Time to vet them a little better at the range tomorrow.

82426

[JCN]

https://youtu.be/RubmcokV7Ms


https://youtu.be/ZurLtsFJlOY


https://youtu.be/XpaeOBW0ZR8

Also if you guys want a cheap 22LR training analog that looks cool, the HK / Umarex 22LR is pretty good.

82841

[JCN]

One nice thing I discovered shooting lefty was that brass ejects forward so no brass to face!


https://youtu.be/IQ8KPwhr-uo

[GJM]

After a USPSA match Saturday, my buddy was gushing about how well his MPX performed. I chuckled and said they sure are awesome until they aren't. Today, three local shooters and friends were shooting PCC at another match. Two of the three MPX carbines failed hard, and ruined their matches. It is not if but when with a MPX, and I would never rely on one for defense.

[TGS]

After a USPSA match Saturday, my buddy was gushing about how well his MPX performed. I chuckled and said they sure are awesome until they aren't. Today, three local shooters and friends were shooting PCC at another match. Two of the three MPX carbines failed hard, and ruined their matches. It is not if but when with a MPX, and I would never rely on one for defense.

Are these "match guns" that are modified, stock shooting light loads, or stock guns shooting "robust" loads like NATO or +p?

There's two federal LE agencies I know of who have adopted the MPX. Just checked with the lead FI from one (who is a member here but tends to not post about his own job), and he says they've been reliable. The quirk seems to be that they needed SIG to replace a number of the guns' pistons to be tuned for the lightweight frang ammo they're mandated to shoot at their range...so they've got some setup for frang as training/qual guns, and the rest for duty.

His words, "They run like a top".

The reason I ask you is that it seems like most of the bad stuff I hear about the MPX comes from PCC competitions, and more often than not they're modified guns as competition guns tend to be, and usually shooting loads optimized for low recoil and not self-defense/duty. I'm wondering if we've had enough time with the platform in the wild to draw a causative correlation......

[GJM]

Are these "match guns" that are modified, stock shooting light loads, or stock guns shooting "robust" loads like NATO or +p?

There's two federal LE agencies I know of who have adopted the MPX. Just checked with the lead FI from one (who is a member here but tends to not post about his own job), and he says they've been reliable. The quirk seems to be that they needed SIG to replace a number of the guns' pistons to be tuned for the lightweight frang ammo they're mandated to shoot at their range...so they've got some setup for frang as training/qual guns, and the rest for duty.

His words, "They run like a top".

The reason I ask you is that it seems like most of the bad stuff I hear about the MPX comes from PCC competitions, and more often than not they're modified guns as competition guns tend to be. I'm wondering if we've had enough time with the platform in the wild to draw a causative correlation......

The modifications are after market triggers, and perhaps a Radian charging handle. I am not aware of anyone "tuning" the MPX, like is often done with blow back carbines.

They run "like a top," until they don't. I have had four, currently have two of the latest Gen.

[JCN]

The modifications are after market triggers, and perhaps a Radian charging handle. I am not aware of anyone "tuning" the MPX, like is often done with blow back carbines.

They run "like a top," until they don't. I have had four, currently have two of the latest Gen.

My current is a few thousand rounds in.

After I “tuned” my MPX to my ammo, I haven’t had a single failure of any kind.

I might be singing a different tune when things fail in the future.

But currently, ammo / bolt / feeding is now perfect after tuning.

It would choke hard when I tried running it before tuning.

I don’t think it’s a gaming platform for people who don’t like deconstructing and problem solving.

Again, I might be singing a different tune if I have trigger failures or barrel failures. But ammo wise I’m 100% over the last 2000 rounds.

I just took the time to really understand failure points in the beginning and tuned there.




I have another one that’s suppressed Steel training only and that fucker is gassy.


https://youtu.be/1Y0o3PjXHHY

The tune on that is different since it’s a dedicated steel practice gun.

Looks like the gas is escaping from the frame between the upper and lower joint in the rear.

Silicone on the charging handle above and below prevents it from going straight into my face though.

TGS yes this gun is set up for the 90gr frangible. Do your guys also have watering eyes from face gassiness?

[JCN]

The reason I ask you is that it seems like most of the bad stuff I hear about the MPX comes from PCC competitions, and more often than not they're modified guns as competition guns tend to be, and usually shooting loads optimized for low recoil and not self-defense/duty. I'm wondering if we've had enough time with the platform in the wild to draw a causative correlation......

I think most of the choking MPXs are guns NOT OPTIMIZED for the gamer loads and that’s why they choke.

Some people think they can use a stock gun designed for a certain range of ammo power and torture that parameter and neglect to realize they run out of margin for when things get dirty or compromised.

Basically Lawman power and up its fine.

Go below that and you have little to no margin and it’s going to choke.

I’m 99% shooting 150 Syntech and it still makes 150 power factor. But it was choke city before I tuned.

Now I can run even down to 127 power factor Eley PCC with margin and reliability.

[JCN]

84376

All three are set up differently and run specifically on the range of ammo it’s tuned for.

Left is my dry and match gun set up to run 127 PF Eley.

Middle is steel range practice set up to run the 90 gr frangible suppressed.

Right is my practice gun set up to run 150 PF Syntech.


https://youtu.be/82OW4FliMVM

[GJM]

In my first two MPX carbines, I competed with Lawman 147 which was approaching 160 power factor out of the carbine length barrel. In my two newer MPX carbines, I used 115 American Eagle, which was 138 power factor out of my five inch CORE, and obviously a lot more out of the long barrel. All those guns and loads ran great, until they didn’t. I never shot anything but factory, and primarily those two loads, in my MPXs.

[JCN]

In my first two MPX carbines, I competed with Lawman 147 which was approaching 160 power factor out of the carbine length barrel. In my two newer MPX carbines, I used 115 American Eagle, which was 138 power factor out of my five inch CORE, and obviously a lot more out of the long barrel. All those guns and loads ran great, until they didn’t. I never shot anything but factory, and primarily those two loads, in my MPXs.

Do you have recall your cleaning regimen and rounds to failure / mechanism of failure?

I’m assuming your gun was 100% stock.

I follow the Enos maintenance guidelines for cleaning and oil.

Lawman power ammo seems to work pretty well with stock internals but still needs fairly regular cleaning and lubing.

[JCN]

All sorts of things around the firing pin, firing pin string, extractor and gas system. I am not even counting triggers which are tough in the MPX and blow back AR9 guns.

Sig can be tough on parts. When I broke a firing pin spring before Area 2 a few years ago, they only had two springs in stock, and sent me them to the wrong place, forcing me to use my second MPX as a spare parts gun and hope I didn’t break another spring. ILWT has carried MPX parts, as a source other than Sig. An issue with Sig is they often don’t want to send parts, they want you to return the whole gun.

If you are a serious competitor, I think you want three MPX guns, so can practice with one, compete with another and have a third for back up or parts.

Ha! Looks like I’m in good shape. I do this anyway regarding low round count match guns and high round count practice ones (got that tip from Max Michel).


Sunday JM Campbell and I got to shoot on a friends property and I took the opportunity to try a variety of loads in my 8' gen2 MPX before detail stripping and cleaning the gas piston. Each was a 25 round magazine:


1) Blazer 115 grain FMJ - multiple malfunctions
2) Speer Gold Dot 124 grain +P - No malfunctions
3) Speer Lawman 115 Grain +P FMJ - No malfunctions
4) Federal Synthtech 150 grain Coated Truncated Cone - Multiple malfunctions
5) Winchester Ranger 147 grain bonded JHP - Multiple malfunctions
6) Federal American Eagle 124 grain FMJ - No malfunctions
7) Federal White box (LE Contract) 147 grain TMJ (truncated cone) No malfunctions
8) Magtech 115 grain FMJ - No malfunctions

It seemed the hotter the ammo the better it ran and it seemed to work best with the +P stuff.

Anyone else had similar experiences with their MPX ?

I've got a few thousand rounds on the gun (Mostly Magtech 115) so I'll try and repeat this after cleaning the gas piston and compare results.

Clusterfrack didn't you mention using anti-seize of the piston in one of the PDW threads ?

My agency has adopted the MPX and just issued a 9 page cleaning and maintenance procedure which includes cleaning the gas piston.


It must have been someone else using anti-seize. GJM? I don’t have an MPX, but my buddy has a troublesome one that does not work well with anything below 140 power factor.

I don’t think anything under about 160 PF is going to be reliable stock. I know I changed some things to add reliability margin when shooting 127-150 PF to get it to run.



I think (but haven't done any kind of study on this) that some of the MPX problems lie with ammo, and people not understanding the MPX. For Prod/CO guns, or blowback PCCs, a lighter powder charge is going to shoot softer. Putting this super soft ammo in the MPX is not the best idea. The MPX is gas operated. It needs gas to run. It likes more gas. More gas gives you more of an operating margin. In that respect, it's more like an open gun. Of course, SIG hasn't helped anything with their perpetual rolling changes.

Things I would keep an eye on are the extractor parts (have spares of that spring/o-ring) and keep the piston/gas expansion chamber clean. Oh, and oil the carrier.

This. Or you have to change a couple things in the system to compensate.

[JCN]

I think the two are different concepts with different solutions.

Reliability: once set and optimized, does it run 99.9+% or does it have intermittent non-wear related failures?

Durability: do things wear or break? Well sure they do. The question is at what replacement interval and is it predictable and preventable?

For competition the Max Michel advice was a low round count big match gun and a higher round count backup gun.

He will send out his guns to be completely rebuilt every off season. The big match gun rotates into a practice gun and a third newer gun will enter the rotation.

I think it sounds like earlier versions of MPX equipment suffered from both the reliability and durability issues, hence the infamous Sig rolling upgrades.

I never know if recommended replacement intervals are BS or something to adhere to.

Having a practice / local match gun helps with that because I don’t replace stuff until it breaks.

And I can move the big match internals to the practice gun and buy new parts for the big match gun.

Looking at what broke on GJM gun and that ILWT says the bolt is a wear part at ~18-20k rounds, I ordered their spare bolt carrier group they have available. That way firing pin and springs are covered as well as loose bits and parts that could get lost or broken.

Even if I had to order a whole new competition gun yearly, I’d be fine with that. It’s that sweet of a gun.

Will compare to the JP5 when mine comes in March. If it proves to be reliable, I don’t think I’m going to switch from the MPX.

[JCN]

Practice gun: 2000-3000 of Syntech 150
Dry gun: 100 of Eley PCC
Frangible gun: <500 (this one I don't really consider part of the rotation, but it's available as a spare if needed).

Parts broken: 0
Items replaced due to wear: 0
Malfunctions after the initial tuning: 0

Cleaning regimen:
Complete disassembly of bolt carrier group with cleaning and oiling every ~500-700 rounds
Remove barrel and gas port for detail cleaning (gunsmith picks are awesome for this) every 1200-1500 rounds or before an away match.

We have a few top 10 PCC guys locally and a number of top 30-50 to compare against, so I don't really travel out of my region. When I was shooting CO, I had a low round count dry gun but my practice gun was very reliable so I never had to bring out the dry gun for matches. I did replace slide stops fairly regularly for the Shadow and I sourced an upgraded pin to use that was very durable.

I'll keep a tally of wear and breakage items with general round counts. I don't count specific rounds, I just estimate by the half-cases disappearing out of the closet....

It'll probably be between 15-30k rounds this year on the practice gun.

[JCN]

Practice gun: 3500 of Syntech 150

Parts broken: 0
Items replaced due to wear: 0
Malfunctions after the initial tuning: 0

Another 500 rounds or so.


https://youtu.be/Da2f8Q33eok


https://youtu.be/hrz97zvhxiY

Going to clean it tonight because bored.

[JCN]

Start to finish about 1.5 hours including using a pick to chip away all the carbon in the piston system.

I’ll keep better track of round counts. During the season I might just clean every two weeks or so.

[JCN]

So the MPX has a reputation of being maintenance heavy so I’m not pushing the limits. I would imagine that as the piston system gets gunked up there can be less margin for reliability with weaker ammo even with reliability tweaks.

If it became prohibitive, I have the following back up solutions that I can / will pull into play:

I have three complete 8” barrel and gas system assemblies.
I have two additional gas systems from the 4.5” and 16” barrel.

I could theoretically just swap dirty piston and cap assemblies and then soak and ultrasound a pile of them together.

I haven’t run into reliability issues even when running it dirty so I won’t go there yet, but I have options in case.

The internal piston parts really do need a pick to get clean.

[JCN]

Not surprisingly, when cleaning the gun and putting things back together including the barrel, the zero gets kind of off.

85330

15 yards, first 5 shots after cleaning.

After getting the gun warmed up and chugging along.

And adjusting zero…

85331

I might just do Bill Drills and close up mag changes right after a cleaning to get things to settle in before trying to chase zero.

[JCN]

85383

[JCN]

Practice gun: 4000 of Syntech 150

Parts broken: 0
Items replaced due to wear: 0
Malfunctions after the initial tuning: 1 (second to last round jam in new 20 round plus extension)

Another 500 rounds or so.

[/QUOTE]

Going to maybe see how far I can push this one without cleaning. Might use one of the other ones for matches so I don’t have to clean it as often and mess with rezeroing.

[JCN]

Practice gun: 4500 of Syntech 150

Parts broken: 0
Items replaced due to wear: 0
Malfunctions after the initial tuning: 1 (second to last round jam in new 20 round plus extension). Vetted the mags again and they function 100%.

Another 500 rounds or so.

I’m just keeping track of when I have to open new half cases of ammo and logging here.

I had a high volume practice session today to really try and lock in my mental cadence and ergos on Blake drills.

I haven’t put this many rounds this rapidly in years due to injury and pandemic but the MPX doesn’t aggravate my wrist like high volume pistol.

85691

I might try soaking and ultrasound cleaner.

[HCM]

Practice gun: 4500 of Syntech 150

Parts broken: 0
Items replaced due to wear: 0
Malfunctions after the initial tuning: 1 (second to last round jam in new 20 round plus extension). Vetted the mags again and they function 100%.

Another 500 rounds or so.

I’m just keeping track of when I have to open new half cases of ammo and logging here.

I had a high volume practice session today to really try and lock in my mental cadence and ergos on Blake drills.

I haven’t put this many rounds this rapidly in years due to injury and pandemic but the MPX doesn’t aggravate my wrist like high volume pistol.

85691

I might try soaking and ultrasound cleaner.

Is that the factory muzzle break ?

Or Taran Tactical ?

[JCN]

Is that the factory muzzle break ?

Or Taran Tactical ?

That one is the TTI which is kind of a right hand design with asymmetric up ports.

Here it is compared to factory which is a more traditional side port brake.

85697

On my dry gun I have a 1/2-28 adapter and cheapo compensator that’s kind of a cross between the two.

85699

[HCM]

That one is the TTI which is kind of a right hand design with asymmetric up ports.

Here it is compared to factory which is a more traditional side port brake.

85697

On my dry gun I have a 1/2-28 adapter and cheapo compensator that’s kind of a cross between the two.

85699

I was looking at the TTI because my local shop just got in an IOP program 16 inch MPX but it lacks the comp and the Timney trigger.

[JCN]

I was looking at the TTI because my local shop just got in an IOP program 16 inch MPX but it lacks the comp and the Timney trigger.

If you want, I can sell you the factory comp pictured above and Timney for a good price.

[JCN]

85704

Pre-soaking the comp in undiluted Simple Green.

[JCN]

85715

Probably did something judging by the water…

Checked and much improved but maybe halfway clean?

Putting it back for another 20 minutes.

This is feasibility testing to see if I can throw all the parts in an ultrasonic cleaner and walk away for an hour and have it completely clean without any effort except a rinse and a wipe.

If so, that would make ownership and maintenance less onerous.

EDIT:

Changed water, added more Simple Green, put back in for 30 more min.

[Default.mp3]

85715

Probably did something judging by the water…

Checked and much improved but maybe halfway clean?

Putting it back for another 20 minutes.

This is feasibility testing to see if I can throw all the parts in an ultrasonic cleaner and walk away for an hour and have it completely clean without any effort except a rinse and a wipe.

If so, that would make ownership and maintenance less onerous.

EDIT:

Changed water, added more Simple Green, put back in for 30 more min.What is it made out of? Might be able to just chunk it in some CLR and let that soak the carbon off. CLR is what many suppressor companies recommend for carbon removal from sealed cans, and seems to work decently IME with SureFire cans and brakes.

[JCN]

85724

Much better.

Will keep going…

Let’s try another 30 minutes

[JCN]

85726

Getting there.

Changed the water and going another 15 min.

This comp had seen the full 4500 rounds of practice plus the initial 200-500 of break in and tuning without cleaning.

So it’s kind of more than I would have to do for piston parts I think.

I did a little light poking with a scoop to break a couple of big chunks loose after I took this picture.

I’m going to stop after this 15 min treatment is done.

[JCN]

85731

I’m good with that. Pretty easy to toss in the cleaner and walk away.

At least I have an idea of the range of time for worst case scenario.

Compared to this:

85732

[JCN]

85738

8” barrel will fit in my ultrasound cleaner.

[JCN]

https://www.preppergunshop.com/sig-sauer-mpx-16-rifle-30rd-9mm-side-folding-stock?mc_cid=a5e6acc8e3&mc_eid=e1cecd0393

[JCN]

Practice gun: 5000 of Syntech 150

Parts broken: 0
Items replaced due to wear: 0
Malfunctions after the initial tuning: 1 (second to last round jam in new 20 round plus extension). Vetted the mags again and they function 100%.

Another 500 rounds.

85822

Watching the carbon build up on the compensator again, lol.

No additional malfunctions. But wondering when I should just do the BCM spring and donut O-ring on the extractor before I have an issue.

[JCN]

I have a bunch of stuff coming up that’s more important so why not clean.

Things look okay for 1500 rounds. I could probably go another 1500 without malfunctions but I don’t want to chance it.

Going to try the ultrasonic cleaner today for the gun parts.

85959

[JCN]

Put moving parts and barrel things in the ultrasound for 20 min while I brushed out and cleaned the upper and lower.

Was pretty good in 20 min and could have put things back together like that, but I’m feeling lazy and changed water and put it in for another 20 min.

If it takes time but not effort, then I’m good with that.

EDIT:

Very good but kiddo wants to play dinosaurs so I added another 20 min (total 60) and we’ll be done.

EDIT:

This is 60 min of no touch cleaning

85960

[JCN]

Still required some pick work in the piston chamber to break up some carbon.

Will try some Teflon spray first to see if I can reduce some of the carbon build up.

[JCN]

For handguns I know the striker and firing pins are supposed to be clean and dry to prevent trapping and attracting dirt and grime with oils and grease.

But I’m kind of a noob to longer guns.

I had been cleaning and leaving the gas system dry.

Oiling the entire BCG.

This time I’m experimenting with Teflon for the piston system instead of nothing.

I did Teflon for everything and did oil on top for the BCG.

I also paid more attention to barrel wobble and torque of the barrel bolts.

I think I wasn’t tightening them enough before. There’s wobble until they get reasonably tight. I didn’t realize that they don’t just retain the barrel, they clamp on the barrel to prevent movement up and down.

I might try and go 3000 rounds between cleanings this time and I’m hoping that the zero is closer, earlier with more attention to barrel clamping.

[JCN]

Practice gun: 5500 of Syntech 150

Parts broken: 0
Items replaced due to wear: 0
Malfunctions after the initial tuning: 2 (second to last round jam in new 20 round plus extension). Trigger didn’t reset once during this session, it could have been my lazy trigger finger short stroking.

500 rounds today since cleaning last night.

The barrel still needed some settling in and it’s fucking with my head.

I think I’m going to do what someone said and clean the piston system with the barrel in place with a deep socket next time.

[JCN]

GJM
Clusterfrack

FYI

Piston socket is a 7/16th.

These are the tools I used to get to the system with leaving the barrel in place.

I used a 5mm socket to cup the piston rod so it wouldn’t slip off so I could gently tap it out.

85978

Not sure if the Teflon helped any.

This is what the gas system looked like after 500 rounds.

85979

This is what I’m cleaning the receiver part on the barrel after gas parts removed.

85980

Regular bore stuff. Brass brush and jag with patch. Rubber banded to keep it on with up and down movement.

[JCN]

One of my tappet gas rings looks worn / damaged with a larger gap between the arms.

Ordered some replacement gas rings for the tappet and the gas blocks.

Thinking maybe I replace some worn stuff at 7500 rounds.

Ideally I’d like to push to an even 10,000 rounds before replacing stuff but that might be pushing it.

[JCN]

Practice gun: 5500 of Syntech 150

Parts broken: 0
Items replaced due to wear: 1
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50

Malfunctions after the initial tuning: 2 (second to last round jam in new 20 round plus extension). Trigger didn’t reset once during this session, it could have been my lazy trigger finger short stroking.

My OCD got to me and I decided to open the gun up again and remove the tappet and gas block, swapping them for a low count set from my 16” barrel. When the replacement rings come in from ILWT ($7 for 9 rings), I’ll swap them. Will keep this gas set for the next ~5000 rounds or so and then swap back for the fresh ring set.

86000

See the missing part with the blue arrow

[JCN]

Practice gun: 5750 of Syntech 150

Parts broken: 0
Items replaced due to wear: 1
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50

Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, it could have been my lazy trigger finger short stroking or worn trigger springs.
3. FTE… might be time to replace the extractor spring and donut.

86033

[JCN]

Practice gun: 5750 of Syntech 150

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, it could have been my lazy trigger finger short stroking or worn trigger springs.
3. FTE, will replace the extractor spring and donut.

86038

I generally like having a clean dry fire gun that lives at home plus a practice gun plus a match gun with low rounds.

Especially with a new platform when I don’t know the failure and wear patterns.

So initially I bought three but because Sig is Sig, one of the grips is a little different.
That one has a slightly different handguard because Sig was out of the 8” handguards and I got a Midwest industries one that puts the front hand stop in a slightly different location.

I did find that Sig is selling uppers and have the Coyote 8” handguards.

I have parts to make a complete separate upper for matches and can keep the practice upper for practice.

[JCN]

Practice gun: 6000 of Syntech 150
Rounds since cleaned: 250

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, it could have been my lazy trigger finger short stroking or worn trigger springs.
3. FTE replaced the extractor spring and donut.

New parts work great. Zero hiccups at all. Feels tight.

First on target 0.08 split.

86092

[JCN]

86139

Amassing the maintenance parts

Spare complete bolt carrier that’ll go into a spare upper to make a match upper.

Spare tappet and gas plug, tappet rings, firing pins and springs, gas plug rings, trigger springs, extractor spring upgrade, spare trigger and spare recoil springs.

[JCN]

86191


https://youtu.be/kgKe5hhrS6E

Super controllable… wonder if the extra maneuverability would be worth it for USPSA.

[JCN]

Practice gun: 6250 of Syntech 150
Rounds since cleaned: 500

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, it could have been my lazy trigger finger short stroking or worn trigger springs.
3. FTE replaced the extractor spring and donut.

[JCN]

86247

There wasn’t an option for the black 8” handguard in stock so I got the coyote.

I wanted it to match exactly ergonomically. The color doesn’t bother me.

[JCN]

Practice gun: 6450 of Syntech 150
Rounds since cleaned: 700
Match upper: 200

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, it could have been my lazy trigger finger short stroking or worn trigger springs.
3. FTE replaced the extractor spring and donut.

I tried using the green dot today outside for the first time and it was hard to see. Will try some other colors but might have to back to red.

Put together the match upper and won’t clean the practice upper until it chokes.

86283

[GJM]

Competitor in my squad today had his Taran MPX malfunction on multiple stages. Gas system just cleaned. Another friend, who shoots a MPX in USPSA just gave up and bought a Brekke AR9.

[JCN]

Competitor in my squad today had his Taran MPX malfunction on multiple stages. Gas system just cleaned. Another friend, who shoots a MPX in USPSA just gave up and bought a Brekke AR9.

Without knowing what exactly they are or aren’t doing for cleaning or maintenance, that’s the worst kind of anecdotal information.

When Harrington has 50k+ rounds on his and continues to shoot it on super squad, that means something.

If you can find out actual information about what a cleaning and maintenance schedule a competitor is using or not using when that has failure, that’s helpful.

Someone who orders a “ready made” $7k version of an MPX that can be done for $2500…

I wouldn’t be surprised if his failed because he didn’t keep up with the $5 part maintenance. People who buy ready made overpriced builds often don’t understand how to upkeep them.

GJM ask him how many rounds since he replaced his gas rings and extractors. If he gives you a “gas what/extractor what?” I would not be surprised.

Continuing to pot shot without actual information about what any why reminds me of this comment from CECIL BURCH:


Cecil Burch

It would be really cool and truly refreshing that when someone tries to put up [information] to support their preferred narrative they also showed that at the same time they understood that the plural of anecdote is NOT proof.

[JCN]

So Max Leograndis had a failure on his JP5 that he won nationals on.

During nationals.

In an interview later he sheepishly admitted that he didn’t clean the extractor in 15k rounds.

Why would anyone skip that at the most important match of the season?

Without them telling you, you just won’t know how careful they are.

That’s where department armorers may be doing a better job than competition shooters if you don’t explicitly know what the schedule is.

[JCN]

I’m not sure what other people are doing for gas system cleaning.

I’m not going to assume that they are or aren’t doing it completely.

It seems IMO something that could be done incompletely if not meticulous.

Like Default.mp3 suggested I might try soaking the gas parts in CLR.

Using simple green and ultrasonic cleaner it took an hour and still required picks and Q tips.

My current procedure is Hoppes spray and dental picks. Finish with Q tips until no carbon.

Brass brush to piston / tappet.

Without picks, it would be easy to think it would be clean but still have areas of carbon left.

I know I’ve thought I was done, only to run a final pick and chunk off more carbon.

[GJM]

You may be the only person in America smart enough to keep a MPX running.

[JCN]

You may be the only person in America smart enough to keep a MPX running.

Compared to all the department armorers and LEO agencies that have declared them good to go with primary data and experience?

I care about data over anecdotes.

It seems that with a prescribed cleaning and maintenance schedule takes care of the reliability issue in the experience of the LEO and military.

I’m following that lead.

If someone is following that lead and having failures, I really want to know about it. Potshot agenda anecdotes, not so much.

But regardless, if someone is dumb enough to buy a $7k MPX and only have one versus getting practice and match guns with tons of spare parts for much less…

You can’t fix stupid.

[GJM]

You have experience with a few personally owned MPX carbines, with a relatively low round count. Glad they are working out for you.

I started shooting a pair of MPX carbines the first year they were out, that first year PCC became a provisional division. Shot them at local matches and Area match competition. Subsequently, I have two of the latest generation, one of which has SBR paperwork. I have observed dozens of them being shot by fellow competitors over the years.

Universally, people love them for their soft shooting characteristics, right up until they crash. The cool thing about USPSA, is you get to observe with your own eyes, what runs and what doesn't run. Now maybe it is like VC3, where folks just aren't smart enough to use it correctly, but there are lots of problems. What are you seeing in terms of MPX reliability with your fellow competitors?

[JCN]

Now maybe it is like VC3, where folks just aren't smart enough to use it correctly, but there are lots of problems.

Something “working until it doesn’t” is nonspecific.

I don’t doubt that many gamer people have and will have failures with it.

But the dissonance is that many LEO / military agencies ARE NOT having failures with them.

Without that critical piece of information I would take your or my anecdotal information as “the best we have.”

But with that critical piece of information, we are left with an alternate explanation.

By this time, I think people can understand that I am very good at problem solving.

If gamers are doing (or not doing) something that leads to additional rates of failure, that’s the focus.

What’s the difference?

Do me a favor and instead of reporting failures, try and add to the knowledge base of what caused the failure.

I personally don’t know if I’m going to have failures or deem it unreliable.

But the biggest database of success is in agency use, so I’m seeing if I maintain the gun in that way… what’s my failure rate.

It’s prospective study. I’m not making any conclusions about my experience yet.

On Enos it seemed like the MPX failure people seemed to be of a certain low frustration tolerance personality type. Some people bitch about maintenance and don’t enjoy the tinkering part. This may not be the gun for them.

[JCN]

Are these "match guns" that are modified, stock shooting light loads, or stock guns shooting "robust" loads like NATO or +p?

There's two federal LE agencies I know of who have adopted the MPX. Just checked with the lead FI from one (who is a member here but tends to not post about his own job), and he says they've been reliable. The quirk seems to be that they needed SIG to replace a number of the guns' pistons to be tuned for the lightweight frang ammo they're mandated to shoot at their range...so they've got some setup for frang as training/qual guns, and the rest for duty.

His words, "They run like a top".

The reason I ask you is that it seems like most of the bad stuff I hear about the MPX comes from PCC competitions, and more often than not they're modified guns as competition guns tend to be, and usually shooting loads optimized for low recoil and not self-defense/duty. I'm wondering if we've had enough time with the platform in the wild to draw a causative correlation......

GJM this is the base of knowledge I am working off of.

A little more information on exactly what is failing on these gamer people’s guns would help advance knowledge. “Run until they don’t” isn’t helpful.

Next time an MPX fails please ask: “how many rounds on the extractor spring and donut, how many rounds since you replaced the tappet gas rings?”

Those two pieces of information would help clarify types of failure.

Both seem to need replacement at the 5K mark to me and are a whopping $7 to replace total for both.

[HCM]

You have experience with a few personally owned MPX carbines, with a relatively low round count. Glad they are working out for you.

I started shooting a pair of MPX carbines the first year they were out, that first year PCC became a provisional division. Shot them at local matches and Area match competition. Subsequently, I have two of the latest generation, one of which has SBR paperwork. I have observed dozens of them being shot by fellow competitors over the years.

Universally, people love them for their soft shooting characteristics, right up until they crash. The cool thing about USPSA, is you get to observe with your own eyes, what runs and what doesn't run. Now maybe it is like VC3, where folks just aren't smart enough to use it correctly, but there are lots of problems. What are you seeing in terms of MPX reliability with your fellow competitors?

A few thoughts:

Like Leupold, SIG is notorious for making “rolling changes” to address issues without public ally acknowledging them. So the MPX of a few years ago may not be the same as the current MPX.

Our maintenance requirements for the MPX at work have changed, current requirements are a full cleaning every 500 rounds. This is lower than the prior round count, however, I think the reduced cleaning interval is based on the fact some of the issued MPX are suppressed and we want one standard for all MPX. Another factor is our purple 9mm training ammo produces (IMHO) excessive carbon fouling.

Essentially we are soaking the bolt / gas piston parts in G96 CLP and getting all the carbon off.

[TGS]

You have experience with a few personally owned MPX carbines, with a relatively low round count. Glad they are working out for you.

I started shooting a pair of MPX carbines the first year they were out, that first year PCC became a provisional division. Shot them at local matches and Area match competition. Subsequently, I have two of the latest generation, one of which has SBR paperwork. I have observed dozens of them being shot by fellow competitors over the years.

Universally, people love them for their soft shooting characteristics, right up until they crash. The cool thing about USPSA, is you get to observe with your own eyes, what runs and what doesn't run. Now maybe it is like VC3, where folks just aren't smart enough to use it correctly, but there are lots of problems. What are you seeing in terms of MPX reliability with your fellow competitors?

The shortcoming in this observation and making decisions off of it is that you keep failing to qualify what "crash" is.

I understand and appreciate that you notice they stop working at a certain point, and I don't doubt that. The important question is, "why?". No gun runs forever without PM and parts replacement. Perfect example: the M60 failed in reliability testing against the M240 because the parts replacement schedule was ignored, which includes some little bits at 15k rounds for the bolt. US Ordnance looked at the test data and found almost all of the failures were after the 15k round mark, and that in particular the guns failed to complete testing because of breakages in the bolt group. When US Ordnance protested this and the test was performed following parts replacement schedule, it was actually more reliable than the M240.

Another example specific to small guns: James Williamson of Teufulhund Tactical (you might remember him from your days on HKPRO) has noted that failures with the HK MP7 are almost exclusively the result of failing to clean the gas piston on the factory proscribed schedule.

So, is it fair to shit on the MP7 because "it works fine until it doesn't"? Is or fair to shit on the M60 because it "works fine until it doesn't"? Granted it seems like SIG might not be very forthcoming with information regarding service intervals, but the reason I'm following JCNs documentation of this service life is because it seems like there might be a reason for MPXs universally failing at a certain point, and if true then that can help the shooting community at large much more than repetitive verbatim posting of, "It works fine until it doesn't" without any qualification or quantification.

[Mike C]

I think the major takeaway from HCM, TGS and what JCN is posting is that there is a significant difference in inspection, preventative maintenance, general maintenance and cleaning as well as replacement schedule for wearable items. I think that this is the predominant difference between gaming/personal use and MIL/LE. I won't speak to large departments or agencies as that isn't my wheel house but on the MIL side we have a procedure for everything, especially freaking maintenance.

So generally speaking when we have an issue crop up it is known what caused the issue and what item failed or is in need of replacement, (as TGS pointed out well) but most often this is mitigated through proper preventative maintenance. This is extremely important and an aspect that is likely ignored by many gamers going from just shooting pistols to a closed system that recirculates hot gasses and carbon back into the gun. I'm not saying that everyone does or that it is the root cause but I wouldn't be surprised if a lot of new to PCC folks are treating their PCC's like a pistols.

[GJM]

The problem is, folks can't figure out exactly what is causing the problems. Frequent cleaning, changing parts and still the guns choke. If we knew the exact cause, we would fix the issue, because the MPX is a joy to shoot. Many of the folks having problems are very sophisticated about guns and maintenance. Perfect example is a long time open GM friend, who has been in the game for decades, career engineer who builds his own Open pistols and AR9 carbines. Loves the MPX but it keeps going down on him in matches.

Not sure if you see Taran, who sells custom MPX's is involved in a new direct blow back AR9. That is a clue.

If military/LEvusers are really doing that level of pm at 500 rounds, it is an issue for competition shooters, who might shoot that much in a single practice or match.

[HCM]

The problem is, folks can't figure out exactly what is causing the problems. Frequent cleaning, changing parts and still the guns choke. If we knew the exact cause, we would fix the issue, because the MPX is a joy to shoot. Many of the folks having problems are very sophisticated about guns and maintenance. Perfect example is a long time open GM friend, who has been in the game for decades, career engineer who builds his own Open pistols and AR9 carbines. Loves the MPX but it keeps going down on him in matches.

Not sure if you see Taran, who sells custom MPX's is involved in a new direct blow back AR9. That is a clue.

If military/LEvusers are really doing that level of pm at 500 rounds, it is an issue for competition shooters, who might shoot that much in a single practice or match.

We were doing the gas system cleaning at 3-5k but the combo of dirty practice ammo and some suppressors drive more frequent cleaning.

From an organizational POV the MPX mirroring the M4 manual of arms makes the higher level of maintenance worth the stretch. Plus our average MPX user will shoot less than 1k rounds per year through it.

[JCN]

The problem is, folks can't figure out exactly what is causing the problems. Frequent cleaning, changing parts and still the guns choke. If we knew the exact cause, we would fix the issue, because the MPX is a joy to shoot. Many of the folks having problems are very sophisticated about guns and maintenance. Perfect example is a long time open GM friend, who has been in the game for decades, career engineer who builds his own Open pistols and AR9 carbines. Loves the MPX but it keeps going down on him in matches.

Not sure if you see Taran, who sells custom MPX's is involved in a new direct blow back AR9. That is a clue.

If military/LEvusers are really doing that level of pm at 500 rounds, it is an issue for competition shooters, who might shoot that much in a single practice or match.

Hence this thread.

Rather than petulant piping, figuring out what’s going on.

There’s obviously a sweet spot between what leo is doing that works and what gamers are doing that doesn’t.

If you really care about your GM friend rather than your ego, send me his info or direct him to this thread to weigh in.

Do you want to fix the problem or does your ego want to support your narrative?

Because while you like to point out flaws and problems, I almost never see you figure out solutions that don’t involve bailing and ditching.

[GJM]

We were doing the gas system cleaning at 3-5k but the combo of dirty practice ammo and some suppressors drive more frequent cleaning.

From an organizational POV the MPX mirroring the M4 manual of arms makes the higher level of maintenance worth the stretch. Plus our average MPX user will shoot less than 1k rounds per year through it.

I have long maintained that if M4 reliability was similar to AR9/MPX reliability, our guys would be in a world of hurt. What did Pat Rogers routinely do, run an AR for 15-20,000 rounds with just adding lube?

I just hung up with a smart friend with a bunch of MPX experience. He said two things were essential. Routinely cleaning the gas system and using a hone to remove build up. Second, go to a heavy AR extractor spring, and change that more frequently than every 1,000 rounds.

[JCN]

I just hung up with a smart friend with a bunch of MPX experience. He said two things were essential. Routinely cleaning the gas system and using a hone to remove build up. Second, go to a heavy AR extractor spring, and change that more frequently than every 1,000 rounds.

HAHAHA!

A friend called it.

He said the first thing you’d do is to call someone to find out basically the same thing we have been saying here.

He’s saying exactly what I’m saying / doing and I’m getting 5000 rounds on the extractor spring.

So now when you encounter a failure will you ask the two things I asked you to find out (which is exactly what he told you).

[GJM]

Hence this thread.

Rather than petulant piping, figuring out what’s going on.

There’s obviously a sweet spot between what leo is doing that works and what gamers are doing that doesn’t.

If you really care about your GM friend rather than your ego, send me his info or direct him to this thread to weigh in.

Do you want to fix the problem or does your ego want to support your narrative?

Because while you like to point out flaws and problems, I almost never see you figure out solutions that don’t involve bailing and ditching.

JCN, would you speak to people the way you do, if you were in the same room with them?

[JCN]

JCN, would you speak to people the way you do, if you were in the same room with them?

Oh I absolutely would for you.

You’re the worst type of megalomaniac.

You’d rather preserve your ego than help others.

It’s my least favorite type of person and anyone who knows me in person knows I would say it directly to your face.

[Mike C]

The problem is, folks can't figure out exactly what is causing the problems. Frequent cleaning, changing parts and still the guns choke. If we knew the exact cause, we would fix the issue, because the MPX is a joy to shoot. Many of the folks having problems are very sophisticated about guns and maintenance. Perfect example is a long time open GM friend, who has been in the game for decades, career engineer who builds his own Open pistols and AR9 carbines. Loves the MPX but it keeps going down on him in matches.

Not sure if you see Taran, who sells custom MPX's is involved in a new direct blow back AR9. That is a clue.

If military/LEvusers are really doing that level of pm at 500 rounds, it is an issue for competition shooters, who might shoot that much in a single practice or match.

I'm going to call bs on this one. Failures don't just randomly happen. Issues can always be traced back to a root problem during the cycle of function. I.E. extraction, ejection or feeding issues. There is generally a specific part that is the root cause or a few parts stacking to create or creating the issue or issues. That is why you go back through the weapon in question and narrow down what part in the cycle of function where the failure is occurring. It is fairly easy to narrow down the part or parts that are responsible from there. I don't have a dog in this fight. In fact I'm not a huge Sig fan though admittedly I own many of their products now and swore them off previously. Still think they are shitty about a lot of things. Hell, I don't even have my MPX yet, (still en route). But you can't vaguely say there are issues then say that there is no rhyme or reason for the failure and no one can figure it out. That is just ridiculous. Sorry.

[HCM]

I have long maintained that if M4 reliability was similar to AR9/MPX reliability, our guys would be in a world of hurt. What did Pat Rogers routinely do, run an AR for 15-20,000 rounds with just adding lube?

I just hung up with a smart friend with a bunch of MPX experience. He said two things were essential. Routinely cleaning the gas system and using a hone to remove build up. Second, go to a heavy AR extractor spring, and change that more frequently than every 1,000 rounds.

The MPX is essentially an adaptation of the MCX to 9mm. In real rifle calibers, using ammo with rifle powders, the system is self cleaning.

9mm doesn’t generate enough pressure to truly self clean and pistol powders burn less efficiently meaning they are “dirtier.”

We’ve not noted extractor spring issues but it’s certainly possible our come with a heavier extractor spring. See prior comments about SIG rolling changes.

[JCN]

86306

Delivered today to make another complete upper.

I’m mainly data gathering.

To limit failure during important matches and to be able to push failure, having low round count match equipment makes sense and is the recommendation of Max Michel.

If the gun is reliable for me with 2000 round cleanings and 5000 round small part replacements, that would be fine.

But it’s data gathering, hypothesis testing and not anecdotal reporting.

[Mike C]

86306If the gun is reliable for me with 2000 round cleanings and 5000 round small part replacements, that would be fine.

I don't think that this is an unreasonable expectation so long as you ad lube as necessary though that may not even be a huge thing.

[JCN]

We’ve not noted extractor spring issues but it’s certainly possible our come with a heavier extractor spring. See prior comments about SIG rolling changes.

One thing that I don’t know is whether soft gaming ammunition could reduce tolerance of the part design, requiring that some parts need to do more with less when less velocity or power is involved.

In problem solving and hypothesis testing, usually the best things are limiting variables.

Whatever repair and maintenance schedule I come up with, might need to be modified with different ammo and powder combinations. It’s also possible my barrel length preferences could also make a minor impact.

[GJM]

I'm going to call bs on this one. Failures don't just randomly happen. Issues can always be traced back to a root problem during the cycle of function. I.E. extraction, ejection or feeding issues. There is generally a specific part that is the root cause or a few parts stacking to create or creating the issue or issues. That is why you go back through the weapon in question and narrow down what part in the cycle of function where the failure is occurring. It is fairly easy to narrow down the part or parts that are responsible from there. I don't have a dog in this fight. In fact I'm not a huge Sig fan though admittedly I own many of their products now and swore them off previously. Still think they are shitty about a lot of things. Hell, I don't even have my MPX yet, (still en route). But you can't vaguely say there are issues then say that there is no rhyme or reason for the failure and no one can figure it out. That is just ridiculous. Sorry.

Due to rolling changes, a first Gen MPX is quite a bit different than subsequent generations. As a result, there are a number of different problems.

In my first two, I was breaking the firing pin spring. You would get intermittent failures to ignite, and disassembly would give you two pieces of the firing pin spring instead of one. Sig then went to a design without that spring, then redesigned again bringing the spring back. The gas system also evolved.

This is from MPX manual on Sig's website.

86313

Says to clean carbon residue with a rag and solvent. No mention how often or using a tool like my friend does. Similarly, there is no mention of an extractor spring, no less replacing one with a stronger one from an AR. If Sig believed cleaning the gas system with a tool and changing to a different extractor spring, they ought to provide those directions, a cleaning tool and extra extractor springs with a replacement interval specified. Of course if the cleaning interval for the gas system is really in the hundreds of rounds, and the extractor spring is +/- 1,000 rounds, that seems like a design that needs to be improved, if the MPX is going to be reliable in the hands of many users.

[JCN]

I posted over a week ago that I’m picking with dental cleaning picks


I’m not sure what other people are doing for gas system cleaning.

I’m not going to assume that they are or aren’t doing it completely.

It seems IMO something that could be done incompletely if not meticulous.

Like Default.mp3 suggested I might try soaking the gas parts in CLR.

Using simple green and ultrasonic cleaner it took an hour and still required picks and Q tips.

My current procedure is Hoppes spray and dental picks. Finish with Q tips until no carbon.

Brass brush to piston / tappet.

Without picks, it would be easy to think it would be clean but still have areas of carbon left.

I know I’ve thought I was done, only to run a final pick and chunk off more carbon.


Still required some pick work in the piston chamber to break up some carbon.

Will try some Teflon spray first to see if I can reduce some of the carbon build up.

It’s pretty common cleaning protocol.

But not necessary if you use the PROPER solvent.

And I’m using the BCM AR spring for the extractor. It’s cheap and easy.


Says to clean carbon residue with a rag and solvent. No mention how often or using a tool like my friend does. Similarly, there is no mention of an extractor spring, no less replacing one with a stronger one from an AR. If Sig believed cleaning the gas system with a tool and changing to a different extractor spring, they ought to provide those directions, a cleaning tool and extra extractor springs with a replacement interval specified. Of course if the cleaning interval for the gas system is really in the hundreds of rounds, and the extractor spring is +/- 1,000 rounds, that seems like a design that needs to be improved, if the MPX is going to be reliable in the hands of many users.

As mentioned here earlier. If someone doesn’t understand that clean means clean and you accomplish that with what you need to get the job done… this might not be the platform for them.

Which was my point when I questioned what your friend actually meant by “cleaning” his gas system.

I trust that when I clean something, I actually verify it’s clean.

You can do that with picks or solvent. I chose picks.

[Mike C]

Due to rolling changes, a first Gen MPX is quite a bit different than subsequent generations. As a result, there are a number of different problems.

In my first two, I was breaking the firing pin spring. You would get intermittent failures to ignite, and disassembly would give you two pieces of the firing pin spring instead of one. Sig then went to a design without that spring, then redesigned again bringing the spring back. The gas system also evolved.

This is from MPX manual on Sig's website.

Says to clean carbon residue with a rag and solvent. No mention how often or using a tool like my friend does. Similarly, there is no mention of an extractor spring, no less replacing one with a stronger one from an AR. If Sig believed cleaning the gas system with a tool and changing to a different extractor spring, they ought to provide those directions, a cleaning tool and extra extractor springs with a replacement interval specified. Of course if the cleaning interval for the gas system is really in the hundreds of rounds, and the extractor spring is +/- 1,000 rounds, that seems like a design that needs to be improved, if the MPX is going to be reliable in the hands of many users.

I will not deny that there have been many iterations of parts. This is undoubtably what makes Sig, Sig and why I feel I must vet everything I buy from them and have shit loads of parts on hand for everyone of the particular variants I own. Unlike Glocks. Having said that I still fail to see how the above equals the below quote. If a firing pin is breaking due to stress or a weakness in design or manufacture I would be looking at what is causing that stress and breakage, composition of the firing pin, metallurgy, manufacture process etc. to fix the issue. That is a very specific breakage you are talking about now, same thing with extractor issues, or gas rings or tappet. Previously you generalized and it is not reasonable to assume no one can figure it out. There are indeed people keeping them running with stock parts used in high firing cycles supressed and non suppressed as well as people running them with aftermarket parts who are generally just maintaining that balance of parts, and springs weights.

I want to talk more about the Agency/Armorer aspect. I know that there is a lot of palm greasing and jobs lined up for people exiting when the MIL or a large Agency lines up a new contract but regardless of that when major agencies adopt it is likely that the system is mature enough for adoption and shows reliability within a set of parameters specified by that agency in mean time between failures, part replacement interval cost over life of contract etc. More often than not that expectancy far surpasses average shooters. In addition to that places where Agents or Officers get trained or qualified regularly they tend to figure out what the issues are in short order with regards to the design if not caught during trials and can either request a design change to fix the short coming or fix that through PM. More often that not with the way modern manufacturing runs we see this change trickle down to everyone.

Either is an acceptable result to me so long as I get a gun that works reliably and I know when I must or should change parts. Of this we can absolutely agree upon. Sig has done their absolute worst in this regard, among being honest about failures of the past. Between that and rolling changes it is hard to keep up. I wouldn't fault anyone for being upset about that at all I was/still am despite buying some of their stuff now. I believe JCN is going down this rabbit hole because of the lack of information and I know I will once I can get my hands on one or three. I appreciate the info, it is unfortunate that we are not able to glean more info from Agencies regarding function, maintenance and costs analysis. Hey does anyone know if we can FOIA that!?


The problem is, folks can't figure out exactly what is causing the problems. Frequent cleaning, changing parts and still the guns choke. If we knew the exact cause, we would fix the issue, because the MPX is a joy to shoot. Many of the folks having problems are very sophisticated about guns and maintenance. Perfect example is a long time open GM friend, who has been in the game for decades, career engineer who builds his own Open pistols and AR9 carbines. Loves the MPX but it keeps going down on him in matches.

Not sure if you see Taran, who sells custom MPX's is involved in a new direct blow back AR9. That is a clue.

If military/LEvusers are really doing that level of pm at 500 rounds, it is an issue for competition shooters, who might shoot that much in a single practice or match.

[JCN]

Practice gun: 6500 of Syntech 150
Rounds since cleaned: 750
Match upper: 230

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, it could have been my lazy trigger finger short stroking or worn trigger springs.
3. FTE replaced the extractor spring and donut.

Zeroed the match upper.

86323

With the shorty, I can’t see the coyote when I’m shooting so it doesn’t bother me at all.

[GJM]

I was just speaking with another friend, and apparently there is a feed ramp issue with certain MPX carbines that affects reliability.

[JCN]

I was just speaking with another friend, and apparently there is a feed ramp issue with certain MPX carbines that affects reliability.
<lighten up or keep it technical, this is is a tech forum, thanks LL>

The feed ramp issue is an old Gen issue.

[S Jenks]

Screen shots from a scanned MPX Armorer’s Manual. Hopefully it loads via Tapatalk and is legible. If not I’ll try again tomorrow, when I’m at a computer. https://uploads.tapatalk-cdn.com/20220320/770f9f16c33c674ea3bd15643d2b7925.jpg
https://uploads.tapatalk-cdn.com/20220320/77dd416f76e8e92aae0e2f007b0a3715.jpg

[JCN]

Screen shots from a scanned MPX Armorer’s Manual. Hopefully it loads via Tapatalk and is legible. If not I’ll try again tomorrow, when I’m at a computer.

Thank you!

[JCN]

I bought an MPX as an MCX training analog but was so much fun that I decided to compete in USPSA with it. I still have 30k+ in Syntech 150 gaming ammo from my CO days.

I read as much as I could on Enos from competition gamers and the people who had success with reliability seemed to be meticulous in their cleaning regimen. I wasn’t sure if I wanted to do that. It also seemed that return springs and extractor springs needed some attention.

But wanting to see what would work for me with my ammunition and my use patterns I set out to answer some questions.

1st phase run up was to see if the gun would work with my ammo. So I took it to the range without cleaning or lubing to try and see where and how it failed when it did. I tested it with different power ammo and when it choked with weak ammo, I tested different ranges of power to see where the envelope of function was regarding gas to spring. It’s not just “if” something works, it’s how much reserve is left in the system when talking about reliability.

Then I broke it down and cleaned it to see where wear was starting so I could identify where I should pay attention to.

I fully cleaned the system, oiled and then started initial durability testing.

I stayed on a LEO / MIL type cleaning regimen for the first 5000 rounds or so (which is what some of the successful MPX gamers do as posted on Enos) to get data of “would it be reliable with that cleaning regimen?”

It seemed to be reliable and I seemed to be well inside the operating balance and margin on that regimen but I’d like to extend that longer if possible… but I don’t want failures in matches.

When it comes to gaming and instruction, I only like to role model off people with sustained success and achievement.

Max Michel is a multi-national CO champ and he has a philosophy of competition guns that I have used in the past for carry guns.

He has one low count match gun and a higher count practice gun. Then in the off season he’ll get them rebuilt, but move the match gun into the practice gun role and often bring in a new gun to be the match gun.

The old practice gun could be a dry gun or whatever.

So in phase 2, where I try and test the limits a little more that’s kind of what I’m trying to do.

I have a sense and S Jenks confirms that 5K extractor springs is a reasonable replacement interval and I’ll have it broken down for cleaning anyway so no biggie for a $2.50 part.

Will also think about tappet gas rings at 5K ($7) part going forward.

But as the round counts escalate, I’ll keep an eye on the other items on the armorer’s list. I’m thinking that if I get 50k rounds on a gun, that’s reasonable life expectancy. So I’m keeping that in mind as a potential retirement benchmark.

Here is what I have to work with for 2022:
I will probably shoot between 15-30k this year.

86331

Primary match gun will see most of the rounds. It has a high round count practice upper that I can stretch the cleaning intervals and try and push the envelope a little. I would like 2000-3000 rounds between cleanings. I will add drops of oil to the BCG when it looks dry.

There’s also a match upper that will only be used for competition. I anticipate that it’ll stay probably under 5-8k rounds for the year.

In a pinch, my dry gun is zeroed and ready to use as a backup for a match. It could also be used next year as the live fire gun and this year’s live gun “retired” to dry fire.

I also have a complete spare new upper and low round count lower for future years.

So that’s the plan. Will modify as data comes in.

[JCN]

So it breaks down into:
5K extractor spring, firing pin spring

10k firing pin, bolt carrier group, gas piston and rings, recoil springs, hammer and trigger pins and springs

20k gas plug and it says barrel, haha.


It gives me tiers of potential failure and wear.

I ordered some additional gas pistons and gas plugs. I’m glad I have a practice gun to play with.

[JCN]

Practice gun: 7000 of Syntech 150
Rounds since cleaned: 1250
Match upper: 250

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, it could have been my lazy trigger finger short stroking or worn trigger springs.
3. FTE replaced the extractor spring and donut.

Put an enclosed emitter on both guns and with the Wheeler laser both were pretty dead on.

Did a bunch of 7 yard speed drills with A zone accuracy and seeing 0.09-0.11 splits with some regularity now.


https://youtu.be/cTrbv-bzYTo

[JCN]

Practice gun: 7000 of Syntech 150
Rounds since cleaned: 1250
Match upper: 250

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.

So a quick amendment. I figured out the trigger reset thing with the help of Mike C since I’m a long gun noob. Turns out I had installed the trigger pins in the wrong order and the legs of the hammer spring weren’t on top of the pin. So when it would walk out it would dead trigger.

I’ll keep it listed in the malfunction list but it’s not really the gun’s fault.

Similarly the first failure was probably the new mag extension binding a little and it’s been 100% since.

So really just the one FTE at 5750 rounds that didn’t recur after the extractor spring and donut were replaced for cheap.

I’ll probably replace the firing pin and spring next. Maybe at 10k rounds.

[JCN]

Thanks to S Jenks armorer’s info, I ordered more tappets and gas plugs. Also barrel securing screws. Thank goodness for Rob at In Lead We Trust. Awesome customer service, he answers my questions almost immediately and super quick shipping. I don’t think I would own MPXs if his store didn’t exist.

86411

I should be good on spare parts for a while.

I have 30k+ rounds left but I kind of want to make it to 50k on the practice gun.

So I bought another 6k Syntech to supplement.

[JCN]

For some of the parts that Sig recommends replacing early replacement of like the entire bolt carrier group at 10k rounds, I’m probably going to run until they fail… but I don’t count it a failure if the life exceeds the recommended replacement interval.

That’s part of the trick for me. Figuring out what parts still need replacement on schedule (like gas system and extractor springs) and what parts have extended life with gamer ammo.

If the bolt carrier group fails at 30k rounds when it was recommended to replace at 10k, that’s hardly on Sig.

Of course, I’m not going to go to big matches with high round count guns. Just like I like to keep my carry guns clean and at low round counts and have a separate practice gun to leave dirty and abused.

I joked to a friend that the money I saved on P365 recoil springs on my practice gun paid for an entirely new gun. I shot my first P365 RSA until it broke apart. For a practice gun, that’s the point.

[JCN]

Practice gun: 7250 of Syntech 150
Rounds since cleaned: 1500
Match upper: 250

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.


Another drama free range session.

[JCN]

Practice gun: 7250 of Syntech 150
Rounds since cleaned: 1500
Match upper: 350

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.
4. Single FTL with 20 round mag in 30 degree weather with full magazine and tight springs along with current downgraded recoil springs. Not enough oomph to strip next round fully.

So let’s talk about this failure. Mike C had warned me about reduced gas in cold temps for a gun like this.

First shot in 30 degree temps using the match upper and contributing to the issue was a very full and tight 20 round magazine. The springs on that are much stiffer than on the 30 plus extensions.

I am currently using stock magazine springs with extensions and I think the soft springs match with the slow ammo and reduced recoil springs. But they can be out of margin in the cold. I have had similar things happen with CO guns loaded to the brim.

So something to watch for in cold temps with this setup. Download mags or avoid the short mags.

I will be so happy when it’s warm enough to practice outside more. It’ll allow me to test combinations a little better.

[HCM]

Practice gun: 7250 of Syntech 150
Rounds since cleaned: 1500
Match upper: 350

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.
4. Single FTL with 20 round mag in 30 degree weather with full magazine and tight springs along with current downgraded recoil springs. Not enough oomph to strip next round fully.

So let’s talk about this failure. Mike C had warned me about reduced gas in cold temps for a gun like this.

First shot in 30 degree temps using the match upper and contributing to the issue was a very full and tight 20 round magazine. The springs on that are much stiffer than on the 30 plus extensions.

I am currently using stock magazine springs with extensions and I think the soft springs match with the slow ammo and reduced recoil springs. But they can be out of margin in the cold. I have had similar things happen with CO guns loaded to the brim.

So something to watch for in cold temps with this setup. Download mags or avoid the short mags.

I will be so happy when it’s warm enough to practice outside more. It’ll allow me to test combinations a little better.

So this may be a function of the power level of ammo you are using.

It’s safe to assume stock MPX / MPX mags are engineered around +P /NATO spec ammo.

[JCN]

So this may be a function of the power level of ammo you are using.

It’s safe to assume stock MPX / MPX mags are engineered around +P /NATO spec ammo.

Yes, for sure it is a function of the weaker ammo and the weaker springs. The weaker springs don’t have enough energy to slam strip a round off a full pack short magazine in the cold.

Potential workarounds are either lubing cases, using something a little bit hotter like Lawman if I needed a totally full magazine, or downloading magazines. I think I will avoid the 20 round magazines in the cold for this reason. I need to test whether I can get normal function with totally full 40 round magazines in the cold.

An interesting thing is I should have known it might be a problem as when I loaded the chamber, it didn’t seat fully and had to forward bolt with my thumb. If that ever happens to me again, I will take the mag out and download rounds.

More gas would be a solution, but if it only happens in the cold with very full short magazines, it may not be an issue for regular competition. But it is a signal that there isn’t much extra reserve in the system with that regard. For the way I have the gun set up for the ammo I am using of course.

[JCN]

HCM my philosophy on gamer 9mm in the MPX is like putting a 22LR conversion kit on a pistol.

Weaker ammo, weaker recoil springs, weaker mag springs.

I can’t lighten the “slide” like in a 22 kit for pistol so I have to make sure the BCG has as little resistance as possible and keep it cleaned and lubed as a surrogate.

Those have been my design thoughts anyway

[JCN]

The FTL happened with the match upper which isn’t as worn in as the practice upper.

There’s also a possibility that could have contributed too, but I don’t want to have to count on wear to make it function.

Just something to keep in mind that failure parameters could change with break in and wear of parts.

Note that the two total magazine related failures have been with the short 20 round mags plus extensions.

No failures with the 30 plus extensions. The 20s and 20s plus extensions feel noticeably stiffer which is why I used them to launch magazines out of the magwell on reloads.

But they may be less tolerant in the system unless I cut a coil or two off of them.

Will see.

I’m going to put my gun in the freezer and load a 30+10 magazine later.

[JCN]

So I played with gun after freezing it…

And I think the silicone I put on the charging handle (on the match upper when I ran it suppressed) might be partially slowing the bolt at the end of the stroke.

It doesn’t quite feel the same as the practice upper.

Going to swap for the new one and see what that feels like. Just goes to show that every little variable can have inadvertent consequences.

86599

[JCN]

Fuck me, it was the charging handle.

HCM

When I tested the match upper frozen it reproduced the funny binding and lack of bolt closure that I felt today outdoors.

But it never felt like it slammed home in the same way.

So I looked at the charging handle mod I did and it was cushioning and dragging at the end of the stroke (purposely as part of the mod) and it was slowing the bolt at the end.

I changed charging handles and froze it again.

Worked perfectly and felt like my practice upper.

Practice gun: 7250 of Syntech 150
Rounds since cleaned: 1500
Match upper: 350

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.
4. Single FTL with 20 round mag in 30 degree weather with full magazine and tight springs along with current downgraded recoil springs. Not enough oomph to strip next round fully. I think it was the silicone on this charging handle preventing the bolt from closing authoritatively. Swapped to clean one and resolved.

[HCM]

Fuck me, it was the charging handle.

HCM

When I tested the match upper frozen it reproduced the funny binding and lack of bolt closure that I felt today outdoors.

But it never felt like it slammed home in the same way.

So I looked at the charging handle mod I did and it was cushioning and dragging at the end of the stroke (purposely as part of the mod) and it was slowing the bolt at the end.

I changed charging handles and froze it again.

Worked perfectly and felt like my practice upper.

Practice gun: 7250 of Syntech 150
Rounds since cleaned: 1500
Match upper: 350

Parts broken: 0
Items replaced due to wear: 2
Gas system at 5500 rounds while waiting for replacement tappet rings ~$2.50
Extractor spring and donut at 5750 rounds ~$5.00


Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.
4. Single FTL with 20 round mag in 30 degree weather with full magazine and tight springs along with current downgraded recoil springs. Not enough oomph to strip next round fully. I think it was the silicone on this charging handle preventing the bolt from closing authoritatively. Swapped to clean one and resolved.

Interesting. I’ve only ever messed with silicone charging handle on 5.56 ARs.

[JCN]

Interesting. I’ve only ever messed with silicone charging handle on 5.56 ARs.

It’s from when I used it for frangible suppressed.

86606

86607

Clarification, that’s a picture OF the silicone lol.

Because one of the new gas busting charging handles has a gasket underneath too.

So I blobbed some there as well.

I shaved it off now and on wise recommendation will try the reduced gas plug with suppressors instead.

[JCN]

Another example of shooting something milder than was designed and having to make the necessary spring adjustments was when I wanted to shoot 38 special out of my Coonan Compact 357 magnum.

They didn’t offer that swap for the short models so I went experimenting with cut down weaker springs to get adequate cycling and function. But since can’t lighten the slide there isn’t that much static strength to close the slide.

It’s very much like what I have with gamer MPX.

It looks like this:


https://youtu.be/-nckNHwJGuM

[JCN]

Okay. I now have enough gamer ammo on hand to make the 50k mark with this PCC.

I’m at ~8k rounds in 3 months so….

[JCN]

I left the match gun in the trunk with a fully loaded magazine.

Let them get totally cold and went to the range after work and shot without any malfunctions.

So far out of the malfunctions, they were all root cause from user error or aftermarket issues except for the FTE from a worn extractor spring at longer than the recommended factory replacement interval…

[JCN]

Practice gun: 7500 of Syntech 150
Rounds since cleaned: 1750
Match upper: 350

Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.
4. Single FTL with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.


So far I would consider the setup reliable with the ammo and springs I am using.

All failures so far in my hands have been my error or doing except for the single FTL with an extractor spring >5k.

[JCN]

Practice gun: 8000 of Syntech 150
Rounds since cleaned: 2250
Match upper: 350

Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.
4. Single FTL with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.

Ran it with full mags in 30 degree weather.

86813

It’s this dry now.

86814

86815

86817

[JCN]

So if this was my only gun, I would clean it now.

2250 trouble free rounds is good enough without any maintenance.

But this is for SCIENCE!

So I’m only going to clean and oil the bolt. I’m not going to clean the gas system or replace parts until 10k rounds.

[JCN]

86822

86823

86824

86825

86826

86827

86828

86829

86830

[JCN]

Factory manual says:
5K extractor spring, firing pin spring
10k firing pin, bolt carrier group, gas piston and rings, recoil springs, hammer and trigger pins and springs
20k gas plug and it says barrel, haha.

So far I have done 5K extractor spring and tappet gas rings.

At 10k, I think I will do firing pin and spring, gas rings, extractor springs. Because they’re cheap insurance.

Should hit that mark in the next few weeks.

[JCN]

This gun has been pretty stupid reliable with the combination of springs and the ammo I have been using for gaming.

Clusterfrack

8000 rounds and only one malfunction that wasn’t my fault. And that was an ejector spring that I think I compromised in the ultrasonic cleaner when it was past recommended replacement interval.

Does anyone have an issue with me continuing in this thread the way I have been going?

Because I was thinking of moving updates to my training journal if nobody cares. I post updates here because that’s the only way I keep track of round counts. Otherwise I usually just replace things either as they break or seem to start having issues. I’m now past the round counts I would put on a match gun.

It’s simpler for me to not post updates but then the documentation for others will be lost.

If people care, I can continue to keep track here. Otherwise I’m going to default to what I normally do with my competition guns and move to just occasional journal updates.

[Clusterfrack]

This gun has been pretty stupid reliable with the combination of springs and the ammo I have been using for gaming.

8000 rounds and only one malfunction that wasn’t my fault. And that was an ejector spring that I think I compromised in the ultrasonic cleaner when it was past recommended replacement interval.


That's really good. Having a PCC that runs reliably is a significant competitive advantage.

[JCN]

That's really good. Having a PCC that runs reliably is a significant competitive advantage.

Despite all the horror stories, I’m just not having the experience that others have reported. My experience is similar to the LEO experience without nearly the level of fluff and buff.

Which makes me think that gamers are being not so smart or just lazy with their maintenance.

$10 of parts in 5K rounds doesn’t seem like a big ask. I downgrade recoil springs like I do in pistols shooting weak gamer ammo. And cleaning the gun means the gun is actually clean as opposed to thinking it’s clean because cleaning motions were made.

For people who really care and don’t want a separate match gun, having a separate match upper seems to be a good compromise. I’ll probably change trigger springs at 15k rounds. They’re cheap too.

[Bergeron]

Small sample size and all that, but the factory replacement parts interval and the experiences with “gamer ammo” and cleaning/lubrication for the MPX right here in this thread seem to represent a real, valuable, and rare resource.

My uncertainty of the MPX led me to an AR PCC, and I’m very happy-zero regrets, but I’d have loved to have been able to at least find and read this thread back when I first decided to source myself a PCC.

[JCN]

Practice gun: 8000 of Syntech 150
Rounds since cleaned: 2250
Match upper: 550

Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 5
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.
4. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
5. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in. I am thinking that the upper needs some breaking in and doesn’t have much extra margin when magazines are tight.

I think I should put some rounds on the match upper to break things in a little better.

I didn’t clean the bolt parts after running it initially suppressed so I might want to take it down and clean it.

[BWT]

This gun has been pretty stupid reliable with the combination of springs and the ammo I have been using for gaming.

Clusterfrack

8000 rounds and only one malfunction that wasn’t my fault. And that was an ejector spring that I think I compromised in the ultrasonic cleaner when it was past recommended replacement interval.

Does anyone have an issue with me continuing in this thread the way I have been going?

Because I was thinking of moving updates to my training journal if nobody cares. I post updates here because that’s the only way I keep track of round counts. Otherwise I usually just replace things either as they break or seem to start having issues. I’m now past the round counts I would put on a match gun.

It’s simpler for me to not post updates but then the documentation for others will be lost.

If people care, I can continue to keep track here. Otherwise I’m going to default to what I normally do with my competition guns and move to just occasional journal updates.

I’m intrigued but - I enjoy this kind of thing. I don’t know that my uninvolved interest has enough value to merit intense journaling. I thought about an MPX and I enjoy the mechanical and observational side of this.

I figured I’d throw out a thank you, but I’ll follow a journal as well.

[JCN]

Practice gun: 8000 of Syntech 150
Rounds since cleaned: gas 2250, bolt 0
Match upper: 800
Rounds since cleaned: 250

Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 5
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.
4. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
5. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in. I am thinking that the upper needs some breaking in and doesn’t have much extra margin when magazines are tight.

I think the issue with FTL was with magazine #3. Recreated it today. Same number of rounds into the same magazine.
I think the spring was binding on the extension.

Took the mag down and worked the spring a little. Will lube spring if that mag keeps having issues 5 rounds in. So far so good though.


86938

86939

[JCN]

So I’m having issues with the low round count upper. It was a brand new barrel and only had a few hundred suppressed frangible rounds on the bolt.

When I did the initial tuning with the practice upper, I ran a few thousand rounds of Lawman before switching to Syntech 150. I wonder if there was some break in that helped with the reliability.

I didn’t do any of that with the match upper.

Going to split reporting failure by upper.

Practice gun: 8000 of Syntech 150
Rounds since cleaned: gas 2250, bolt 0
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.

———-
Match upper: 1250
Rounds since cleaned: 700

Malfunctions: initial tuning phase
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in. I am thinking that the upper needs some breaking in and doesn’t have much extra margin when magazines are tight.
3. FTL with Syntech and FTE with Lawman.

Good range session today. Shot 250 of Syntech with the match upper fully loading magazine #3 and no failures until the last magazine… another FTL. I still don’t know if it’s that particular magazine. But then shot some Lawman and some frangible and some minor Eley. Had a couple FTE where the cartridges flipped in the upper. So something is a little off in the timing of this mag / upper / ammo combination.

I may put the recoil springs on the tester in case they weren’t properly packaged and they’re stiffer than the normal -25% I use. I also might replace the extractor spring just in case since it’s a $2.50 part and the FTEs are suspicious with the Lawman. But it could be recoil spring and magazine spring interaction.

Also might run some Lawman through it as a tuning and break in.

[JCN]

1. Changed recoil springs to a known pair of -25% “red” painted springs. The ones I had put in weren’t the usual color but calipered appropriately so I had used them. Will go to a known set just in case.

2. Changed extractor spring and post. Unusual that it’d be an issue at this stage but I did initially shoot suppressed with this bolt. And its $2.50 in parts so why not.

3. Changed mag spring and follower from spares I had from my dry mags.

Will run Syntech again and see if any issues.

I’m exercising the recoil spring manually through the full stroke to see if that helps too.

[JCN]

86995

Felt much better and no malfunctions in 250 rounds. Still sub 40 degree weather.

I suspect the other recoil springs might have been not the correct ones.

The failures were ones similar to when I was initially testing the practice upper with factory springs.

As I’ve said before, I usually downgrade recoil springs when using weak gamer ammo. It is a common thing to do with gamer pistols as most factory springs are made to balance with +P or defensive power ammo.

Most gamer ammo is on the order of 380 ACP power.

So imagine the kind of failures you’d have in a 9mm military grade pistol trying to shoot 380 ACP.

That’s what I suspect causes a lot of PCC failures. Sure, some people shoot gamer ammo out of stock MPX after break in but there’s still not as much margin as if you matched springs to load.

An example I had with pistols. I had a Gen 4 Glock 34 that was reliable for me shooting gamer Syntech 150.

But I let a few other people shoot it and they all had malfunctions because their grips were a little less firm. It didn’t affect me but it had less margin in the system. So I went down on spring to restore margin. Even though it was reliable with a stock RSA for me in normal conditions, reliability entails having margin in parts for dirt and inadvertent contact or drag.

So that’s part of my guiding build philosophy.

As part of the gamer MPX build I started off with lower power recoil springs and I feel like that’s a big contributor to my success.

I could explain the recent match upper failures to a mislabeled stiffer spring.

Feels good now and was crisply reliable.

Also put a Radian charging handle and tested that too.

86996

Practice gun: 8000 of Syntech 150
Rounds since cleaned: gas 2250, bolt 0
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.

———-
Match upper: 1500
Rounds since cleaned: 950

Malfunctions: initial tuning phase
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in. I am thinking that the upper needs some breaking in and doesn’t have much extra margin when magazines are tight.
3. FTL with Syntech and FTE with Lawman.
Possible attribution could be mislabeled recoil springs (weren’t painted red).
Changed recoil springs to known red -25% strength and changed extractor spring and post.

Rounds without malfunction: 250

[JCN]

Confirmed with Rob that not all -25% are red.

I’ll stick with the red ones for now since they seem to work. Possible explanations are that it was the mag spring and follower swap that solved the issue or possibly the red paint coating changes the friction and binding of the spring weight. I’m not sure and I don’t know. I usually only change one parameter at a time, but since it was a low frequency malfunction I didn’t want to burn a lot of ammo on the root cause analysis if simple spring replacement got me the reliability I had been enjoying with the practice upper.

[JCN]

Rob from ILWT called me personally today to confirm some order things and made sure I got what I wanted and needed.

More red springs coming!

[JCN]

Practice gun: 8250 of Syntech 150
Rounds since cleaned: gas 2500, bolt 250
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 3
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut.

———-
Match upper: 1500
Rounds since cleaned: 950

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower.

Back to working on the practice upper. Still chugging along. Still <40 degrees out.

[JCN]

So I’ve been running the gas system on the practice upper without cleaning until failure to test.

87100

Had a single FTE (ran fine after) at 2600 on gas system without cleaning and 2500 on extractor spring.

I’m going to clean the gas system and see how the piston rings are holding up.

I think 2000-2500 round gas system cleaning is probably appropriate.

Will see if any FTE after cleaning before I get to 5000 rounds on the extractor spring.

——

Practice gun: 8350 of Syntech 150
Rounds since cleaned: gas 2600, bolt 350
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring

———-
Match upper: 1550
Rounds since cleaned: 1000

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

[JCN]

87128

I decided to remove the barrel to check things out. Some chunks of carbon fell out.

Carbon in the piston system, but rings intact.

Will probably do in place gas system cleaning 2500 rounds and barrel off every 5000 rounds.

These are my favorite picks for cleaning.

87129

Solvents would work just fine, but I have a small child and I would rather use picks than harsh chemicals.

[JCN]

Freshly cleaned. I think 2000-2500 is a good gas system cleaning interval.

Will run it to for another couple thousand rounds and then I’ll start replacing some parts when I hit 10-15k rounds.




——————
Practice gun: 8350 of Syntech 150
Rounds since cleaned: gas 0, bolt 0
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring

———-
Match upper: 1550
Rounds since cleaned: 1000

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

[HCM]

Great Grandpa of the MPX:


https://youtu.be/UiUSGFN7KiU

[JCN]

Practice gun: 8350 of Syntech 150
Rounds since cleaned: gas 0, bolt 0
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring

———-
Match upper: 1700
Rounds since cleaned: 1150

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

Malfunctions after initial tuning:
0

[JCN]

87251

Practice gun: 8850 of Syntech 150
Rounds since cleaned: gas 500, bolt 500
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring

———-
Match upper: 1700
Rounds since cleaned: 1150

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

Malfunctions after initial tuning:
0

[JCN]

Closing in on 10k rounds on the match upper. It’s getting into the 50-60s temperature wise and I think that’s helping reliability over 30 degree weather. Seems to meet my definition of “reliability” so far.





Practice gun: 9300 of Syntech 150
Rounds since cleaned: gas 950, bolt 950
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring

———-
Match upper: 1700
Rounds since cleaned: 1150

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

Malfunctions after initial tuning:
0

[JCN]

Practice gun: 9500 of Syntech 150
Rounds since cleaned: gas 1150, bolt 1150
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring

———-
Match upper: 1700
Rounds since cleaned: 1150

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

Malfunctions after initial tuning:
0

[JCN]

87529

My sense is that things are getting a little dry and if I wanted to add some margin I would add a few drops to the bolt.

I might make a summary in a different thread.





Practice gun: 10000 of Syntech 150
Rounds since cleaned: gas 1650, bolt 1650
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring

———-
Match upper: 1700
Rounds since cleaned: 1150

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

Malfunctions after initial tuning:
0
04-11-2022, 12:18 PMJCN
450 more on practice upper, no malfunctions

Closing in on 10k rounds on the match upper. It’s getting into the 50-60s temperature wise and I think that’s helping reliability over 30 degree weather. Seems to meet my definition of “reliability” so far.





Practice gun: 9300 of Syntech 150
Rounds since cleaned: gas 950, bolt 950
Parts broken: 0
Items replaced due to wear: 2
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00

Rotating gas block and piston together with a second unit every 5K rounds.

Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring

———-
Match upper: 1700
Rounds since cleaned: 1150

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

Malfunctions after initial tuning:
0

[JCN]

Practice gun: 10000 of Syntech 150
Rounds since cleaned: gas 0, bolt 0
Parts broken: 0

Items replaced due to wear:
Tappet gas ring 5500 rounds, $2.50 replacement.
Extractor spring and donut at 5750 rounds ~$5.00
Tappet #2 gas ring 5000 rounds
Gas plug #1, 2 gas rings 5000 rounds ~$12
Firing pin and spring 10000 rounds ~$42
Hammer pins and springs 10000 rounds ~$12
Extractor spring and donut at 10000 rounds


Malfunctions after the initial tuning: 4
1. Second to last round jam in new 20 round plus extension, subsequently no issues.
2. Trigger didn’t reset once during a session, DUE TO MY ERROR INSTALLING hammer spring legs under the pin and the pin walked.
3. FTE replaced the extractor spring and donut at 5750
4. FTE at 2600 on gas system without cleaning and 2500 on extractor spring






———-
Match upper: 1700
Rounds since cleaned: 1150

Malfunctions: initial tuning phase (<1250)
1. Single FTL (match upper) with 20 round mag in 30 degree weather with full magazine attributable to a caulked charging handle not allowing bolt closure. Resolved with stock charging handle and tested in cold.
2. Had another FTL with the match upper with a new 30 round mag and extension that I had not ever used before. I had a FTL about 5 rounds in.
3. FTL with Syntech and FTE with Lawman. Same magazine as #2. Changed recoil springs to known red -25% strength, changed extractor spring and post, changed magazine spring and follower. With no malfunctions after.

Malfunctions after initial tuning:
0