So I was gonna build a 10.5 pistol and the more I read, I decided on an 11.5 upper. Luckily, a fellow hide member gave me a great deal on a BCM Mlock upper in 11.5 with a BCM BCG. I just happened to have a spare complete BCM lower in my safe from some previous trading around. I got it put together added an Eotech, some BUIS, light and some rail scales to tame the heat on this shorty. I also added a Law Tactical folding adapter to make it more portable. My suppressor is a YHM Turbo with the brake muzzle attachment. I knew it would be overgassed so I went ahead and got an H3 buffer for it. Sighting it in, didn’t really notice any gassing but could tell by the ejection pattern it was somewhat overgassed. Yesterday, I took it and put it thru its paces with some really fast drills on steel and it became obvious really quickly that it was overpassed because I was taking it straight to my face. So, last night I went ahead and ordered a Bootleg adjustable BCG as I didnt want to tackle the gas block change on a BCM, they are a pain in the ass. Is this bootleg gonna fix my problem or does anyone have any other suggestions? The Geissele spring and buffer kit looked interesting but I’m not certain it’s necessary. Let me know if anyone has any experience with this setup. FYI, after abt 150 rounds, I have had zero malfunctions with mixed ammo but the gassing is a little too much.
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Suppressed 11.5 pistol build help
- Thread starter tlsmith22
- Start date
Outside of adding an adjustable gas block, you really have to find the ammo that you plan to stick to. In some cases, you may have to decide if you want it to be dedicated to be used for suppressed fire when considering the buffer weights. I’ve settled on an h2 with standard spring.
I’ve had an 11.5 sbr for years. It has a 12.5” barrel cut down to 11.5 so that it would have a slightly smaller gas port size. For the longest time, I didn’t think it was capable of cycling unsuppressed until I Stopped shooting weak ammo. Now, I almost exclusively shoot 55 or 62gr federal ammo (also an Israeli ammo) knowing that it will cycle reliably with or without the can. If you play around with different loads, you might find what could work well for your set up. As for blowback, definitely try the RTV silicone mod to seal up the gas coming out of the charging handle... It helps.
You’ve probably read that the voter a5 system helps with flexibility. I don’t have any experience with it.
Is it a pinned gas block? Is that why you don’t want to mess with it?
I’ve had an 11.5 sbr for years. It has a 12.5” barrel cut down to 11.5 so that it would have a slightly smaller gas port size. For the longest time, I didn’t think it was capable of cycling unsuppressed until I Stopped shooting weak ammo. Now, I almost exclusively shoot 55 or 62gr federal ammo (also an Israeli ammo) knowing that it will cycle reliably with or without the can. If you play around with different loads, you might find what could work well for your set up. As for blowback, definitely try the RTV silicone mod to seal up the gas coming out of the charging handle... It helps.
You’ve probably read that the voter a5 system helps with flexibility. I don’t have any experience with it.
Is it a pinned gas block? Is that why you don’t want to mess with it?
Nice setup btw. I think 11.5” is the best for maneuverability. Definitely fun to shoot
And forgot to add, I tried to see if the Geissele super 42 made any difference for weaker loads. For me it was no different.
And forgot to add, I tried to see if the Geissele super 42 made any difference for weaker loads. For me it was no different.
I plan to shoot it 100% suppressed. I plan to shoot all 55 grain loads, although I tried 62 and 77 and it cycled them fine as well. I get the bootleg tomorrow and I will see if it help and may go ahead and do the RTV mod also.
It’s not a pinned gas block, I think BCM actually red loctite the whole gas block and also the set screws. I took one off and ended up having to cut it off, I couldn’t get it off any other way, thats why I am trying the bootleg first.
Thanks man
It’s not a pinned gas block, I think BCM actually red loctite the whole gas block and also the set screws. I took one off and ended up having to cut it off, I couldn’t get it off any other way, thats why I am trying the bootleg first.
Thanks man
I run a bootleg in my 10.5”. Works great. Run on unsuppressed if no can. But mainly only running with the can. Mine works best one notch from the suppressed setting. All the way to supressed and it won’t lock open on empty mag.
I like it! Nice setup! These short and lightweight suppressed rifles are awesome when you get them right. I love my MK12 and Recce but this is so much easier to carry and mine with the Law Tactical folder fits in a backpack easily.
Gas busters are ok (I’m assuming you’re referring to PRI); rtv should also help. If you end up having to run an adjustable gas block, you may be able to ease the Loctite with a heat gun to remove those bolts.
I have several 10.3's that I run suppressed. I have learned to just accept the gas 
. I use gas buster charging handles and make sure my buffer system is set up correctly. It can be gassy at times, but it is part of the short barreled game. I have heard a lot of good stuff about the bootleg system, but never got one because I dont want to tinker with it. Good luck!
. I use gas buster charging handles and make sure my buffer system is set up correctly. It can be gassy at times, but it is part of the short barreled game. I have heard a lot of good stuff about the bootleg system, but never got one because I dont want to tinker with it. Good luck!
I have the same upper that I run a aac sd556 on as well with a h3 buffer, in my opinion you’re not going to have a dead nuts reliable 11.5 defensive carbine that’s not over gassed when suppressed. So my advice is either buy better hearing protection or just deal with it. The adjustable gas block is fine until you get 500 rounds through it and it’s to corroded to adjust then you’re back at square one. And who the hell wants to tune a block because they added/removed the can, Ya know? I think ideally I’d buy a fancy heavy buffers suppressed buffer/spring and then convert your h3 into a h2 and keep it in your range bag for when you wanna be the asshole with the loudest gun at the range.
So am I following this correctly? Carbine length gas systems on 10.5-11.5in SBR barrels are on the edge of being under gassed when shooting nonsuppressed....but way overgassed suppressed? So you have to build these SBRs with very tunable gas systems so they function reliability?
im building my first SBR and I’m researching these two barrel lengths and how to get them both running reliably suppressed / unsuppressed in a user friendly manner
im building my first SBR and I’m researching these two barrel lengths and how to get them both running reliably suppressed / unsuppressed in a user friendly manner
I now have two identical BCM 11.5“ pistols. One is running a Bootleg BCG and the other is running a Gemtech BCG and both in teh suppressed setting and both with the RTV mod. They went from practically unshootable(but reliable) suppressed simply because you would get gassed so bad. I never had a failure out of either rifle but the gas was intolerable to me shooting fast. I would say both BCGs stopped 75% of the gassing and improved ejection to abt 4, when it was at abt 2. I have not shot either suppressed as my only concern was suppressed.
But if you take all these measures to reduce the back pressure for suppressor shooting what happens when you want to shoot unsurprised? Is the gun now undergassed and not functioning properly?
No, the guns are typically overgassed unsuppressed also, and people select cans with lots of backpressure and get gas in their face. It’s harder to set up short barrels by the way.
Use the longest gas system you can, the smallest port you can and the lowest backpressure silencer you can. In my case it’s an 11.5 carbine +1 with a 5” long can designed for low backpressure. It’s loud but it’s not gassy or hard on the gun.
Use the longest gas system you can, the smallest port you can and the lowest backpressure silencer you can. In my case it’s an 11.5 carbine +1 with a 5” long can designed for low backpressure. It’s loud but it’s not gassy or hard on the gun.
how is a 10.5-11.5in barreled SBR overgassed unsuppressed with such a short dwell time? 16in barreled carbine length Pipes don’t seem to be as overgassed as the shortys
One, because the gas port is larger and taps more gas, and two, the largest reason is that the barrel is shorter so exit pressure at the muzzle is much higher and the gas goes right back down that short bore and through that larger gas port. That’s why a shorty is harder to set up. They go from gassed right to overgassed that much faster when suppressed.
I like dedicated suppressed setups. I’m working on a rifle length gas 16.5” project that will only run with the can in place, using 5.56 pressure ammo. We are going to start with a .070” port and experiment from there. I did a 10.7” .063 with an AAC can and it was wickedly overgassed. Should have been a port in the low .05X range at most I learned later.
I like dedicated suppressed setups. I’m working on a rifle length gas 16.5” project that will only run with the can in place, using 5.56 pressure ammo. We are going to start with a .070” port and experiment from there. I did a 10.7” .063 with an AAC can and it was wickedly overgassed. Should have been a port in the low .05X range at most I learned later.
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