The big 10.5"-12.5" general purpose pistol/SBR thread

[navyman8903]

Why an adjustable gas block on 10.3”? To facilitate operation with a suppressor?

I’d tend to assume that Geissele would know what they’re doing with gassing and buffer selection for a complete gun, so wondering why adjustable..

But I’m really new to ARs, so I don’t know what I don’t know...

No stress man, we've all been there. This is an example of an adjustable gas block. What it allows is adjusting the gas port size essentially. You can set it for unsuppressed, suppressed, single shot, and adverse if memory serves. What it allows for is giving you an additional layer of control over your rifle.

Most if not all 10.3-10.5's are over gassed and the timing is very aggressive. 11.5's are much smoother over all and I don't think you'll find anyone with both or experience on both will refute that. You have to work a lot harder to tame a 10.3-10.5 though it is not impossible. Most people run a sprinco red spring or blue spring with an H3 buffer which is a really heavy setup to offset the severity of the recoil/gas. It'll also increase the lock time and slow the timing down overall. Which will also increase the longevity of your bolt lugs.

But honestly man, I would go with an 11.5. The Geissele even at full price is a screaming deal. Run it with a Super 42 and Geissele H2 buffer. Or a Noveske H2 buffer with a Sprinco Blue spring. You'll be very happy with it.

[ASH556]

Why an adjustable gas block on 10.3”? To facilitate operation with a suppressor?

I’d tend to assume that Geissele would know what they’re doing with gassing and buffer selection for a complete gun, so wondering why adjustable..

But I’m really new to ARs, so I don’t know what I don’t know...

Forget about the adjustable gas block. Are you running a suppressor or not? Why do you want a 10.3 or 11.5 pistol? Just smaller? Either will run just fine with proper gas port sizing (the Geissele 10.3's are DD barrels reported to be .070, so that's good. Their 11.5's are fine as well from firsthand experience with 2 that belong to another member).

I like 10.3 because I want it as short as possible with a full-size can.

[ASH556]

No stress man, we've all been there. This is an example of an adjustable gas block. What it allows is adjusting the gas port size essentially. You can set it for unsuppressed, suppressed, single shot, and adverse if memory serves. What it allows for is giving you an additional layer of control over your rifle.

Most if not all 10.3-10.5's are over gassed and the timing is very aggressive. 11.5's are much smoother over all and I don't think you'll find anyone with both or experience on both will refute that. You have to work a lot harder to tame a 10.3-10.5 though it is not impossible. Most people run a sprinco red spring or blue spring with an H3 buffer which is a really heavy setup to offset the severity of the recoil/gas. It'll also increase the lock time and slow the timing down overall. Which will also increase the longevity of your bolt lugs.

But honestly man, I would go with an 11.5. The Geissele even at full price is a screaming deal. Run it with a Super 42 and Geissele H2 buffer. Or a Noveske H2 buffer with a Sprinco Blue spring. You'll be very happy with it.

Sorry, guess I'm gonna be that guy. Everything you've posted about 10.3's is false.

[navyman8903]

Sorry, guess I'm gonna be that guy. Everything you've posted about 10.3's is false.

I would love for you to list how it is with the years of data assembled on the 10.3's out there. Including user feedback easily accessible from reputable sources.

[awp_101]

I guess lol. I'm not sure what they were thinking.

I've seen other designs where the prongs are sort of twisted or otherwise not centered and dress right dress as a way to modify or reduce the flash. Since the one you have doubles as a suppressor mount I don't know if that twist is part of the design for flash hiding, something to do with running a suppressor, both or if the guy running the CNC that day was off his game.

[texasaggie2005]

I also have a Super 42/H2 combo. It shoots really smooth. Just have that up and to the right push. I looked at the cut of the muzzle device and that's the culprit for sure. I'm going to swap a CTN on it as soon as possible. I really like how its gassed and I think when I get the P4Xi on it, it'll outshoot my SR16 with its barrel profile.

This is why, look at that agro cut at the 4:30 as the device is facing us.

Attachment 54482Attachment 54483

I'm not sure that's the culprit. All three tines are equally spaced 120° apart and equal sized, so I'd assume the blast exiting is equal as well.

I have Surefire's 3P Eliminator on mine, which is the non-suppressor mount of your SF3P. And I actually have a 14.5 upper with a SF3P p&w.

Next time I go shooting, I'll shoot both back to back and see if I feel a difference.

[TGS]

Why an adjustable gas block on 10.3”? To facilitate operation with a suppressor?

I’d tend to assume that Geissele would know what they’re doing with gassing and buffer selection for a complete gun, so wondering why adjustable..

But I’m really new to ARs, so I don’t know what I don’t know...

The muzzle blast will only effect you if you're in close quarters, close to a barricade, that sort of thing. A blaster diffuser/blast forward/linear compensator will direct the blast downrange if you're worried about people next to you.

Or, if you're running suppressed, it's a non-issue, as well as any worry about the possibility of it not being gassed enough.

Just buy what you want, make sure it's set up properly and it will run fine. I didn't buy a DD Mk18 for a couple years because I agonized over what the internet told me about 10.3" barrels, until I finally came to the realization that I/my agency has more experience with properly built Mk18s than the internet, and our experience is basically peaches'n'cream. For all the handwringing on the interwebs about 10.3" barrels, ours just work fine.

Most if not all 10.3-10.5's are over gassed and the timing is very aggressive. 11.5's are much smoother over all and I don't think you'll find anyone with both or experience on both will refute that. You have to work a lot harder to tame a 10.3-10.5 though it is not impossible. Most people run a sprinco red spring or blue spring with an H3 buffer which is a really heavy setup to offset the severity of the recoil/gas. It'll also increase the lock time and slow the timing down overall. Which will also increase the longevity of your bolt lugs.

I would love for you to list how it is with the years of data assembled on the 10.3's out there. Including user feedback easily accessible from reputable sources.

That might be the case with overgassed guns, but a Mk18 with a Crane-spec .070" gas port is not over gassed. As an agency, we run standard springs and H buffers on our several thousand DD Mk18s, no issues, and they're extremely smooth shooting, reliable guns. The smoothness is akin to my BCM 14.5" midlength guns, feels like a .22 magnum. A standard Colt M4 feels like a different caliber when shooting them side by side.

FWIW, most 11.5" barrels have gas port sizes as big or bigger than .070", while having the longer dwell time as well. So, if you think a proper Mk18 is overgassed, that means garden-variety 11.5" guns are way overgassed. That also means they would have increased bolt velocity over the Mk18, which would result in more abrubt recoil, not less, and more parts breakages, not less.

So, I'm not saying that 11.5" guns have those issues, since that's obviously not true. I'm using your own thought process/logic to point out that you're wrong.

[navyman8903]

I've seen other designs where the prongs are sort of twisted or otherwise not centered and dress right dress as a way to modify or reduce the flash. Since the one you have doubles as a suppressor mount I don't know if that twist is part of the design for flash hiding, something to do with running a suppressor, both or if the guy running the CNC that day was off his game.

I think this design works for a 4 prong okay as it is going in 4 opposing directions. My URGI shoots flat without any increased pressure in any direction. Where as the 3 prong, especially on the 11.5 does not work as well. With the 3 directions to go vs the 4 it has to push some way. Also the vents are larger essentially so more force, coupled with the short barrel. I would be interested to shoot it against the Geissele 14.5 or 16" super duty rifles to see if it's as savage an issue.

[ASH556]

No stress man, we've all been there. This is an example of an adjustable gas block. What it allows is adjusting the gas port size essentially. You can set it for unsuppressed, suppressed, single shot, and adverse if memory serves. What it allows for is giving you an additional layer of control over your rifle. Adjustable gas blocks also introduce a failure point to the most critical part of the system that differentiates it from a bolt-action rifle.

Most if not all 10.3-10.5's are over gassed Not if ported correctlyand the timing is very aggressive. 11.5's are much smoother over all Again, depends on porting and who made the barre, but certainly not a blanket statement. Slightly smoother, maybe. Much? No. and I don't think you'll find anyone with both or experience on both will refute that. Me, I refute it. Speaking as a multiple-certified armorer working at one of the largest shops in the Atlanta area on public guns ranging from Colts to Noveskes to whatever the worst garbage you can possibly imagine. I have a pretty good idea of what will run, what won't, and why. You have to work a lot harder to tame a 10.3-10.5 though it is not impossible. Not even close.Most people run a sprinco red spring or blue spring with an H3 buffer which is a really heavy setup to offset the severity of the recoil/gas. False. With a 10.3" barrel ported at 0.070, I run a Colt spring and H2. The gun runs 100% with .223 or 5.56 ammo, suppressed or not. It's plenty controllable. I can run mine at .10-.12 splits across 10 shot strings and hold the black of a B8 at 7yds no issues. It'll also increase the lock time and slow the timing down overall. Dwell time, not lock time and that's only a part of the equation. Gas port sizing plays as much if not more of a factor here. For example, a 16" Carbine-gassed barrel has more dwell time than a 16" midlength, but the mid length is always said to be smoother shooting. Also the mid length has a larger gas port. Which will also increase the longevity of your bolt lugs. Maybe, again depends on other factors

But honestly man, I would go with an 11.5. The Geissele even at full price is a screaming deal. Run it with a Super 42 and Geissele H2 buffer. Or a Noveske H2 buffer with a Sprinco Blue spring. You'll be very happy with it.

There's a start.

[navyman8903]

The muzzle blast will only effect you if you're in close quarters, close to a barricade, that sort of thing. A blaster diffuser/blast forward/linear compensator will direct the blast downrange if you're worried about people next to you.

Or, if you're running suppressed, it's a non-issue, as well as any worry about the possibility of it not being gassed enough.

Just buy what you want, make sure it's set up properly and it will run fine. I didn't buy a DD Mk18 for a couple years because I agonized over what the internet told me about 10.3" barrels, until I finally came to the realization that I/my agency has more experience with properly built Mk18s than the internet, and our experience is basically peaches'n'cream. For all the handwringing on the interwebs about 10.3" barrels, ours just work fine.






That might be the case with overgassed guns, but a Mk18 with a Crane-spec .070" gas port is not over gassed. As an agency, we run standard springs and H buffers on our several thousand DD Mk18s, no issues, and they're extremely smooth shooting, reliable guns. The smoothness is akin to my BCM 14.5" midlength guns, feels like a .22 magnum. A standard Colt M4 feels like a different caliber when shooting them side by side.

So I'm not refuting your experience. The 11.5 Geissele uses a .068 vs their 10.3 using the .070. The 10.3's I've shot are noticeably rougher on recoil and timing. I've run more than a few to include LMT, DD, a BCM 10.something and a few other 10.5's. There are also plenty of 10.3's out there with broken bolt lugs. Which was the highlighted issue with the 10.3's is the reduced internal parts life. I'm not saying it's impossible to get one to run right, there's just a few steps you have to take and the gas port size is important. I would submit that any length gun with an improper gas port size for the length/gas system length will be miserable to shoot.

The only smooth 10.5 I've fired was a noveske with an adjustable gas block both unsuppressed and suppressed.