.22LR trainer: conversion bolt vs dedicated upper vs 15-22

[TicTacticalTimmy]

As the title suggests, I am looking at getting a 22lr for the sole purpose of cost-effective training to acquire skill with my ar-15. I'm looking at all the different options, and would like feedback from those who have already gone down this road.

My current thinking is to buy the CMMG conversion bolt, a few cmmg/blackdog mags, and the Borebuddy reliability upgrades. I'll also be getting a Primary Arms red dot that I will zero for 22lr. That should allow me to switch fairly quickly at the range between 5.56/.22lr, and the handling characteristics would be identical to my normal AR except for no recoil.

Down the line I figure that I will buy a 22lr barrel and collar to improve the accuracy and turn my upper into a dedicated .22lr upper. That would happen after I build a 2nd 5.56 upper, which at current prices I could afford to do after shooting <2000 rounds of 22lr instead of .223. That is my thought process / justification.

The S&W M&P 15-22 seems like it will be the most reliable and easiest solution. However, by the time I buy furniture and a trigger to replicate my real gun, the cost would be the same as buying the conversion kit and then a complete upper down the road. For all that it will be much lighter and balanced differently so I don't feel it will translate over to 5.56 skill as easily.

Thoughts/suggestions?

[Suvorov]

I have a dedicated CMMG upper receiver that I built into a .22LR AR. This was largely done because in the state of Kalifornia a rim fire rifle is NOT considered an assault weapon and therefor I can configure it as I want. I also did it because the better accuracy potential of a .22LR barrel versus running a conversion bolt with a .223/5.56 barrel. All in all I have mixed feelings on the build and am not sure I would do it again. The pros are that the rifle feels every bit like a full caliber AR and I can configure it exactly how I want (rails, stocks, ect that may not fit on a M&P 15-22). The downside is that it has not been as reliable as I would like. The big issue here is it's inability to extract an unfired round from the chamber. I have tried to polish the chamber and tried several different types of extractors that are supposed to solve the problem but to no avail. Short of reaming the chamber I'm at a loss. Additionally I have not had good luck with all the CMMG add-ons that add AR functionality like the last round bolt hold open, are not worth their trouble and only add to the rifle's unreliability. I have found that good ammo and black dog magazines will give me almost acceptable reliability. I really never did notice an huge improvement in accuracy over using a conversion bolt although I'm sure it is there.

If I were to do this again, I would probably go the route of an M&P 15-22 or if I lived in a state that didn't have asinine gun control laws, probably stick with a conversion bolt as the one I had had no issues with extraction.

Thanks for the link about the bore buddy upgrades - another rabbit hole for me to spend money on :cool:

[rob_s]

IMO the trigger and stock are irrelevant. I might concern myself with the grip at most. Might.

[John Hearne]

I'm not sure how the price comparison works compared to a quality dedicated upper, but the all metal Tippman gun continue to intrigue me as a dedicated training gun. I like the 15-22 and it is fine for manipulations and gross marksmanship but it seems to lack the accuracy of a 10-22.

https://tippmannarms.com/tippmann-arms-m4-22-elite-tactical-rifle/

[TicTacticalTimmy]

Did you try the Borebuddy weights and buffer plug Suvorov ? My initial research suggests those may be necessary for good reliability:

https://m.youtube.com/watch?v=EmYgZrUQpxQ

[Bigghoss]

I went with the M&P15-22. It's really lightweight which might be an issue but at least it has a last round bolt holdopen. Granted, you have to clip a coil or two off the spring for it to work, but it's there and it does work. I had also considered the Tippman line of .22lr AR rifles/pistols. I went with the S&W just because it was easier to get at the time and so are the mags.

[757_Magnum]

The scarcity of ammo and components led me to build a dedicated 22 SBR build, plus I had a Huntertown Arms Kestrel suppressor that I regret buying. It was my first centerfire can, and the features that make it subpar for 5.56 are great for a 22LR trainer that mimics the handling of its big brothers. I used the 8" barrel and BCG from Right To Bear, which are just rebranded CMMG at a lower price, and the Boonie Packer mag adapter for 15-22 mags, which provides real LRBHO and cheap mags. I just finished it this week, but haven't had a chance to take it to the range.

[Jeff22]

I bought an S&W 15-22 in November of 2009.

I used various models of the M-16 in the service, and have accumulated a number of them since. My first was an SP1 that I bought in 1977.

I bought an Atchisson converter back in 1982 from Bro-Caliber International. I couldn't get it to work at all until I had it tuned by John Norrell in Florida late in 1985. After that, it worked GREAT and has been very reliable and NOT ammo sensitive.

The converter works well, but I was interested in the Colt and Smith & Wesson ARs in .22 as soon as they came out. I have a friend who bought one of the Colt .22s, and I shot it and enjoyed it, but it's complicated to disassemble to clean and the external controls don't work the same as on a "real" AR -- in particular, the bolt catch/release doesn't work at all, and the safety works differently than on the original rifle.

So I bought the S&W M&P 15-22. Best function has been with CCI Mini-Mags or the CCI AR Tactical Rimfire ammo, but if kept clean and lubricated the gun works fine with standard velocity LRN .22. After I had the gun a couple of months, I was firing Winchester Expert .22 ammo and had a round go off out-of-battery. It blew the extractor off. The case was ruptured. We found the case, but not the extractor.

The guy at S&W customer service said that was a common problem at that time (2010). I shipped the gun back (at their expense) and they repaired it and I had it back in two weeks or so.

A few years ago I got a Safariland RLS light & mount to put on the rail of my M&P 15-22. It attaches on the rail at the 9 o’clock position, and the mount curls up and puts the light at about 11 o’clock, which is a convenient place for me to activate the tail cap switch with the thumb of my left hand.

I just got a Vortex Crossfire RDS to put on that gun, but I haven't mounted it yet.

I’ve been real happy with the M&P 15-22 and I’d recommend them to anybody.

[Suvorov]

Did you try the Borebuddy weights and buffer plug Suvorov ? My initial research suggests those may be necessary for good reliability:

https://m.youtube.com/watch?v=EmYgZrUQpxQ

No, actually your post was the first I've heard of them. I kind of gave up trying to figure the gun out a few years back when I decided that given the limited range time I had, I really wasn't doing myself any good by using sub caliber guns and just shot 556 instead. So it only comes out a couple times a year now when I go shooting .22s with my boys. Things may change however if the dems take the White House and the boot of gun control drops to the point that 9mm and 556 stay up close to $1 per round (I've already invested in a .22lr Beretta conversion). Again - thanks for bringing them to my attention.

[Seven_Sicks_Two]

I picked up a CMMG conversion kit with magazine on sale a few years ago. Admittedly, I only have a few hundred rounds through it, but it seems to function fine. That said, I only stock plated high-velocity 22lr (typically 40gr CCI Minimags, although I've shot some Remington through it as well). Accuracy has been fine at the relatively short ranges I shoot it, and the only reliability issue I can recall is a single light strike.

[NGP]

I've got a 15-22 that's at about 10k rounds, most suppressed, I started to have some really odd malfunctions last week only to notice that I at some point lost the extractor. I generously lubed the BCG, and it resumed operating normally, somehow. Keep in mind in 10k I haven't cleaned the gun once, it has been left in my barn, in the dust and humidity, just generally treated terribly, but it has continued to run. Accuracy has been acceptable for my needs, definitely not a .25 MOA gun or anything, but it works well enough. Mag's work great, I haven't had any issues that I can recall, they're easy to load for younger/novice shooters, they also lock back reliably. I wish it were a bit heavier and the rail a bit longer, but overall I've been extremely happy with the 15-22.

[jandbj]

I fooled with a few options in the conversions and dedicated uppers for my AR. In the end I LOVE the 15/22 SBR with now over 30k through it. Mostly suppressed. I too had the OOB extractor flinging event. Probably around the 15k rounds when that happened. I think I’ve only had to detail strip and clean all the gunk out of the trigger group twice in all this time. The 15/22 is by far the easiest choice in a rimfire AR trainer. And it’s a crapload of fun too.

Get a McFadden machine lightnin grip magazine loader for it too.

[Joshmill]

I've been through this a couple of times. I would go dedicated upper. It's probably the most expensive but it's also likely to get used the most because the other options are a pain in the ass.

[TWR]

I've had 2 of the M&P 15-22's, the first one was right after they came out and it had to be sent back for the upgraded spring kit. Ran great for thousands of rounds after that. My daughter would shoot 1100 rounds every Saturday and learned the platform very well. She moved off and I wound up trading it for a 640-1 but I figured I'd get another one someday.

A year ago I bought an M&P Sport model with the Mlock rail on it and it's been flawless. I shoot Steel Challenge with it sometimes and even won the first match I shot with it. It has a B5 SOPMOD stock on it, MagPul K2+ grip, Geissele SSP trigger, KNS pins, a Sig 4H red dot, BUIS's, a light and a few other odds and ends to add weight. I did add a BCM Mod 0 brake to make it louder so the shot timer will pick it up more reliably. It's never choked on any ammo and works exactly like a real AR. I like it.

[Doc_Glock]

Get a McFadden machine lightnin grip magazine loader for it too.

Ordered and really excited to get this!

[littlejerry]

Ordered and really excited to get this!

It's a game changer. You'll need a lot more ammo.

[tango-papa]

As the title suggests, I am looking at getting a 22lr for the sole purpose of cost-effective training to acquire skill with my ar-15. I'm looking at all the different options, and would like feedback from those who have already gone down this road.

My current thinking is to buy the CMMG conversion bolt, a few cmmg/blackdog mags, and the Borebuddy reliability upgrades. I'll also be getting a Primary Arms red dot that I will zero for 22lr. That should allow me to switch fairly quickly at the range between 5.56/.22lr, and the handling characteristics would be identical to my normal AR except for no recoil.

Down the line I figure that I will buy a 22lr barrel and collar to improve the accuracy and turn my upper into a dedicated .22lr upper. That would happen after I build a 2nd 5.56 upper, which at current prices I could afford to do after shooting <2000 rounds of 22lr instead of .223. That is my thought process / justification.

The S&W M&P 15-22 seems like it will be the most reliable and easiest solution. However, by the time I buy furniture and a trigger to replicate my real gun, the cost would be the same as buying the conversion kit and then a complete upper down the road. For all that it will be much lighter and balanced differently so I don't feel it will translate over to 5.56 skill as easily.

Thoughts/suggestions?


Suggest consider a dedicated .22lr AR upper - with your stated long term goal, the end costs will be about the same.
I have a Tactical Solutions AR M4 .22LR Complete upper and it's been very accurate/reliable in that role for several years.

I sourced the TacSol upper from CSTactical (they currently have them in stock at $550).

https://www.cstactical.com/tactical-solutions-ar-m4-22lr-complete-upper

If you get a dedicated 22 upper, at a minimum, be sure to also get a "pressure plug" to keep the bolt properly seated. I have a TACCOM Pressure plug, but from what I can, or more accurately can't find, they are no longer available.

Bore Buddy has a pressure plug along with other "reliability upgrades" as you mentioned, that look to be solid.

[Bigghoss]

Boonie Packer mag adapter for 15-22 mags, which provides real LRBHO and cheap mags.

I wish I had heard about these earlier when I asked about a .22 trainer for my work gun. Ordered one to try out.

[stomridertx]

I went with the newer M&P 15-22 model with the m-lock plastic handguard to use as a trainer. The only investments I needed to make it like my main AR-15 was a Vortex Crossfire red dot, Troy BUIS, a cheap collapsible stock with a QD swing swivel, Magpul MOE-k grip, cheap m-lok qd sling adapter from Botach, and a cheap UTG light mount that mounts a spare Surefire G2X light in the same spot as my much more expensive light on my AR.
I don't regret that purchase for a second. I shoot that gun all the time and my kids love to shoot it. When I'm working as an RSO I let people new to AR-15s shoot it all the time to get them hooked on the platform. It's a fantastic gun, and unlike a conversion it is a useful .22 rifle all on it's own besides being a trainer. The accuracy is really good with mine and there's no reason I couldn't use it as a varmint gun.

[drummer]

I picked up a Tippmann Arms M4-22 Elite last week after finding one in stock. I had been looking for one for a while after hearing positive reports on them. I had originally planned on building a .22 upper using Tac-Sol parts until I heard about the Tippmann.

My requirements were:

16" barrel for training purposes
Metal M-Lok handguard
As close to a AR controls as possible.

I wanted to create/build a .22 AR for training purposes as well as for the kid as she's getting old enough to start shooting. I have also considered doing some Appleseed events and the S&W M&P is banned.

For those not familiar, the Tippmann M4-22 rifles are made by the Tippmann paintball marker company. They've only been out a few years. They are not widely known, but perform well in reviews. The receivers are aluminum (though seem to be cast and not the same quality as a good AR), use (some) AR triggers, have a standard AR BHO, and can use standard AR furniture. The charging handle is plastic but operates as standard, only having a much shorter pull.

Before hitting the range, I pulled the factory iron sights off the rifle (plastic sights similar to M-BUS), installed KAC 600m sights, removed the factory grip for a MIAD, and replaced the shaky factory stock for a CTR. I also installed a picatinny rail for a bipod and a KAC barricade stop. I'm waiting on the M-Lok QD adapter I ordered to show up.

I got a chance to fire it for the first time yesterday at the range. My goal at the range was to get it zeroed with the KAC sights and test function across available ammo. I shot roughly 200 rounds utilizing Blazer bulk pack, Federal Champion bulk pack, Winchester Super-X bulk pack, and crappy old Remington Golden bulk pack. I shot roughly 50 rounds of each. Due to the ammo shortage, I couldn't find any match grade quality to really test accuracy.

I started off with the CCI. Every 10 to 15 rounds it would have a severe malfunction (FTF). The second time it FTF'd, magazine disassembly was required in order to clear it due to the round being stuck in the magazine.

Setting the Blazer aside, I switched to the Federal Champion. Functioning was flawless. It worked very well with the Federal.

I next tried the Winchester Super-X. It was a lead bullet and not plated. The Super-X does not function well in my dad's 10/22 so I was not hopeful in the Tippmann. Surprisingly, it functioned flawlessly also.

Lastly, I finished off a very old box of Remington Golden bullets. I've always considered them one step above absolute junk. The Tippmann even fed the Remington, though it did have one FTF over 50+ rounds fired.

So, upon initial blush, the Tippmann may be a serious contender for a .22 AR trainer. Here's my PRO/CON list:

PROS:
seems to have good accuracy
AR-sized mags fit in mag pouches for training
utilizes some aftermarket AR triggers
AR controls
reliability seems good with the right ammo

CONS:
The factory selector is plastic and sluggish (this is admittedly nitpicky)...they're making a ambi replacement that is steel that I will probably buy. I don't want ambi selectors but hate sluggish selectors on ARs. I would just not install the ambi side.

Like most (all) .22 autos, it can be ammo sensitive.

That's really it. So far, I'm happy with my purchase. I feel that it will provide plenty of fun training for the kid and myself.

[DDTSGM]

I have built two .22LR trainers. One is a service rifle trainer on a dedicated lower and matches my White Oak service rifle pretty closely. CMMG barrel and bolt. I use it for practicing the 100 yard reduced courses. Works flawlessly for this purpose. It's a little heavy for general plinking, but is also used for that. Saves tons of money. I use Bulldog mags in this one.

The other is a complete upper I bought on sale from PSA for grins and giggles. It is an 8 inch and wears a Warrior suppressor. Boonie Packer mag block and S&W mags for this one. It gets shot, a lot. I generally run the Remington Golden Bullet bulk pack in it, but also use Federal Auto-Match bulk packs in it. I'm not going to tell you it doesn't hiccup occasionally when a youngster is shooting it, but I rarely have any problems. The only problem is that even though I have never seen an ATF agent at our range, I have to swap off an SBR lower because I don't do the pistol brace workaround.

For my uses, the dedicated uppers have proven to be the best choice. I can also see that pressing the easy button and buying an M&P makes sense for a lot of folks.

If I was contemplating going to go to the expense of buying a commercial AR 22 and going to the expense of changing parts to match a rifle I already had, I'd definitely go the build your own dedicated .22 trainer route and end up with 7075-T6 receivers that will accept any mil-spec parts.

[TicTacticalTimmy]

Lots of good feedback so far. As expected the S&W 15-22 sounds like the easy and nost reliable way to go, but given my purpose I think the dedicated upper still makes the most sense.

Any comments on the CMMG pattern VS Redi Mag and S&W? I am not going to be doing a dedicated lower anytime soon, so how long it takes to install/uninstall the Redi Mag is a big factor. I dont think I will miss not having LRBHO since I can just practice mag changes with 5.56.

I see you have both Dan Lehr

[DDTSGM]

Lots of good feedback so far. As expected the S&W 15-22 sounds like the easy and nost reliable way to go, but given my purpose I think the dedicated upper still makes the most sense.

Any comments on the CMMG pattern VS Redi Mag and S&W? I am not going to be doing a dedicated lower anytime soon, so how long it takes to install/uninstall the Redi Mag is a big factor. I dont think I will miss not having LRBHO since I can just practice mag changes with 5.56.

I see you have both Dan Lehr

First lets talk about mag differences. The S&W is left, the Black Dog right. (EDIT: Wow that S&W is tiny but you can see the tab on the follower sticking out at the top of the magazine) out

https://cdn3.volusion.com/hnmuk.qprpf/v/vspfiles/photos/SW-19929-2T.jpg?v-cache=1573813294 https://palmettostatearmory.com/media/catalog/product/5/1/5165450746-Blackdog-Xform-Next-Gen-22lr-25rd-Blk-Steel-lip-SW-25BL-SS_1_5.jpg

The S&W magazine is slightly narrower than the mil-spec mag well (I assume to keep someone from putting a real AR mag into the well) and while it will lock into place, it wobbles without the Better Mag. The black Dog Magazine is the same size as the mil-spec magazines and will fit into the mag well with no slop.

The follower on the Black Dog magazine sticks up far enough that it will stop the conversion bolt from coming forward, but it doesn't activate the bolt catch, so when you remove the mag the bolt goes forward.

The S&W mag's follower doesn't stick up high enough to stop the conversion bolt. LRBHO on the S&W is accomplished by the rear tab of the follower contacting the Better Mag adapter's sliding bolt catch which moves up to capture the conversion bolt and activate the rifle's bolt catch. (see PDF below) If the sliding bolt catch is not present in the Better Mag, the magazine will function but when the last round is fired the bolt will go forward on an empty chamber. I mention this because currently my sliding bolt catch is AWOL.

I prefer the S&W mags for plinking use, they are easy enough for anyone to load. At one time they were cheaper and easier to source than the Black Dogs, not really so sure at this point.

As far as ease of installing the Better Mag, it is easy once you get the hang of it. It installs from the bottom of the mag well and is pretty close tolerance so you have to start it level. After it is started into the mag well you have to depress a detent pin to allow further insertion. This was actually what gave me the most problem. Looking at the shape of the detent pin and the bevel on the bottom of the mag well, you;d think just kind of hold the detent in a little to get it started on the bevel and press the adapter in. Doesn't work that way on my rifles, you have to hold the detent in all the way until it is in the mag well.

Here's a link to the Better Mag. Look down the page and there is a link to a PDF for installation instructions.

https://www.redi-mag.com/product/better-mag-s-22-rimfire-magazine-adaptor/

Hope this helps.

[Xrslug]

Throwing this out there as another option that I have seen mentioned elsewhere. I’m interested as I can replicate my service rifle setup pretty easily with this and it’s substantially cheaper than Compass Lake. I haven’t seen a ton of reviews but what I have seen is positive. Apparently a proprietary bolt but similar to the Nordic Comp system:
https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=1972
They have complete rifles as well.

[DDTSGM]

Throwing this out there as another option that I have seen mentioned elsewhere. I’m interested as I can replicate my service rifle setup pretty easily with this and it’s substantially cheaper than Compass Lake. I haven’t seen a ton of reviews but what I have seen is positive. Apparently a proprietary bolt but similar to the Nordic Comp system:
https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=1972
They have complete rifles as well.

It looks like I'm into mine for about $518.00 using current prices. I'll probably add a float tube soon so that will jack the price another $120.00 to $638.00.

[Suvorov]

Palmetto has the Tipman for $500. https://palmettostatearmory.com/tippmann-arms-m4-22-pro-16-22-lr-ar-15-rifle-black-a101034.html?trk_msg=LGGAABJU465KVATOOEG0BP03H8&trk_contact=NFTD246RRLDKSG4SKKI8E0NI74&trk_sid=SFTMPI9LUBC5H8Q4COUJ8IR890&utm_source=Listrak&utm_medium=email&utm_term=SHOP+NOW&utm_campaign=Daily+Deal+Email&utm_content=5%3a00+Email

[ratter75]

I use the CMMG conversion bolt. My reasoning is that it gives me reps with my actual rifle. Aside from the limited “throw” on the charging handle when using the CMMG, the feel and function is identical to going ...ahem...”full bore”. Optic, sling, light, ambi safety, trigger etc. I put too much time, money, and effort into that rifle to put most of my reps into a completely different gun like the 15-22.

Since I get fist-sized groups with it at 50 yards, really the main (only?) benefit is cheap trigger time behind the “real” gun. You aren’t going to be shooting groups with it or hunting groundhogs.

I had a 15-22 and a SIG 522 and found both supremely unsatisfying. Although, for teaching my kids, the 15-22 was the best of the three. Smaller and lighter weight. Less intimidating. But my CZ 455 is better yet for that purpose.

[EricM]

Palmetto has the Tipman for $500. https://palmettostatearmory.com/tippmann-arms-m4-22-pro-16-22-lr-ar-15-rifle-black-a101034.html?trk_msg=LGGAABJU465KVATOOEG0BP03H8&trk_contact=NFTD246RRLDKSG4SKKI8E0NI74&trk_sid=SFTMPI9LUBC5H8Q4COUJ8IR890&utm_source=Listrak&utm_medium=email&utm_term=SHOP+NOW&utm_campaign=Daily+Deal+Email&utm_content=5%3a00+Email

The Elite version of the Tippmann with the longer aluminum rail is also available for $500 here (https://www.smga.com/tippmann-armory/tippmann-arms-m422-elite-tactical-rifle-11923) (no experience with the seller).

I nearly bought one today but ended up ordering a 15-22. The metal construction of the Tippmann appealed to me, but I could see the lighter weight of the 15-22 being an advantage when my daughter is ready to shoot it. Deciding factor though was mag availability.

[TWR]

One should never start adding up what he’s got in a rifle. I don’t remember what I gave for the base M&P but I added decent sights, a Romeo 4H, a B5 SOPMOD stock, a Geissele SSP trigger and KNS pins and I was shocked. Then I thought about the dozen mags I have and flushed the whole thought out of my mind.

[TicTacticalTimmy]

I went ahead and ordered the CMMG Bravo conversion bolt from Primary Arms, along with their ACSS reticle Holosun red dot, and I also picked up a few of the Black Dog "Sonic X" mags which were on sale at Midway.

I took it to the range today and am happy to report it exceeded my expectations! I fired a couple hundred rounds and had a single light strike with Federal Champion, which went off on the second try. I tried Aguila SV, Aguila HV, Federal bulk, Federal Champion, CCI Mini Mags, everything fed and ejected great and shot decently. CCI and Aguila SV seemed to be tied for most accurate with about 2" or so groups at 50yds, with the other loads all going into 3" 5 shot groups at 50yds.

Given that I was shooting a red dot without the aid of a bench I am sure the kit is capable of slightly better accuracy than the above, and I might pick up a magnifier for it to see if I can do a little better. I also want to try it at 100yds and see if the rounds destabilize. As it is, the accuracy is great for shooting drills out to 50yds. I did some near to far transitions and transition drills, and felt I gained as much as I would have shooting 5.56. Overall I am extremely pleased with the reliability and accuracy of this conversion. If it maintains the same precision out to 100yds I don't think I will even bother to get a 22lr barrel as was my original plan.

The only negative I can see is that I did accidentally dry fire a couple times, which I am sure this kit is not meant to sustain. The bolt stops on the follower when you run the mag dry, and when you remove the mag the bolt goes forward into battery. When seating a new mag my brain thought "AR mag seated, bolt is forward, must be round in chamber" and I proceeded to dry fire instead of racking the bolt. Luckily the firing pin is hitting the "chamber insert" instead of the actual chamber, so it isn't something that can damage the actual barrel.

I do still plan on getting some of the Borebuddy upgrades such as the weight for the bolt and charging handle insert. I originally planned on getting their full upgrade kit which includes a "buffer pressure plug" that pushes the conversion kit into the chamber so it doesn't slop around. Unfortunately my lower (NFA integral folding lower) uses a unique buffer and wouldn't be compatible with that item. Fortunately, there doesn't appear to be any slop whatsoever between the conversion kit and buffer, probably a result of the unique buffer poking a bit farther into the upper receiver. I am guessing the fact the buffer in my lower eliminates this slop contributed to the excellent reliability I experienced.

[Bigghoss]

Tried out my CMMG conversion and 15-22 mag adapter in my PSA 10.5" pistol and everything worked great. Accuracy wasn't bad either. When things calm back down I'm going to do a dedicated .22lr for these.

[TicTacticalTimmy]

Took my 22lr conversion out again today. I installed the borebuddy fixed weight, buffer, and charging handle insert. I also replaced the red dot with my PA 1-8 scope. Mainly I wanted to see if the borebuddy upgrades improved accuracy. This isn't really a fair comparison to my last session since I used a magnified scope instead of a red dot, but I had greatly improved accuracy. At 50yds Aguila went into 1.1" for 5 shots, with Federal bulk about 2". However, at 100yds the Aguila opened up more than proportionately, with a 4" 10 shot group. Interestingly, the CCI mini mags opened up about proportionately with a 2.5" group at 100yds. Oddly the mini mags hit about the same elevation, but about 3" to the right at that distance. I'm guessing that past 100yds things will really start to open up, but I really can't complain about that launching 22lr from a 1:7 barrel.
In conclusion I am extremely pleased with the kit. With this level of accuracy I'm no longer interested in getting a dedicated 22lr barrel anytime soon. The conversion, mags, and borebuddy stuff was about $300 total, and I feel is an excellent training platform for the AR, except for longer range shooting, reloading, or anything involving multiple hits on a target.

Notes:
-scope difference was 2.6mils elevation and .1-.2mil windage, should be easy enough to switch between 5.56 and .22lr.
-charging handle insert completely eliminated blowback with aguila, but I still got a tiny bit with cci mini mags. Definitely worth the $10.
-100% reliability, but I only shot about 100 rounds
-For anything resembling precision work, it seems like different loads will hit to very different POI's, so its probably best to find one load that shoots well and buy a whole bunch of it.

[ArgentFix]

I also have a CMMG 22 conversion BCG I bought a few years ago and never opened. Now seems a good time to try it in the backup backup M&P 15 Sport II that I semi-panic bought. I've read naked lead bullets, or plated bullets, or waxed bullets (depending on who you ask) can cause buildup in the gas tube. Any truth to this?

[DDTSGM]

I also have a CMMG 22 conversion BCG I bought a few years ago and never opened. Now seems a good time to try it in the backup backup M&P 15 Sport II that I semi-panic bought. I've read naked lead bullets, or plated bullets, or waxed bullets (depending on who you ask) can cause buildup in the gas tube. Any truth to this?

I don't know, at one time the common recommendation was to shoot a couple .223/5.56 rounds after you are done with the .22 lr's.