Suppressor Back Pressure

[Cecil S.]

Hello Folks , so I am entering the game of SBR and suppressor ownership. NFA , ATF will go through a Kiosk in my area. My question is the back pressure that the "can" adds. I will be shooting an AR style SBR and I understand that excessive pressure out of this style action is like putting your face in front of an exhaust pipe. Just wanted to ask this question to the people with way more knowledge then me at this point. Thank you.

 

[Loudenboomer]

Back pressure although noticeable its not that big of a deal except you will notice how dirty EVERYTHING gets. You didn't mention cartridge type or if sub or super. Choosing a load that will stay clean as possible will save headaches.

 

[JB10]

I notice more gas in my face at the range. I use one on a 16in 223. I rarely shoot it at the range except to make sure its still on for coyote season. When im in the field shooting a predator i never notice the blowback, but not making too many shots in a row.

 

[karrarararararar]

I think the load matters. Shooting 53gr Vmax's with benchmark I have no gas issues. Shooting heavies with slower powders is a different story.

 

[Jdne5b]

It can be, depending on the suppressor chosen. A short barrel 5.56 isn’t easy to suppress. Some very expensive suppressors don’t work very well. Some inexpensive suppressors work very well. Some are low back pressure and some are higher. The newer 3D printing technology is getting pretty crazy and resulting in some performance that blows everything out of the water.

Www.pewscience.com

He also has a ton of podcasts, very technical analysis on the website and podcasts. It’s a good place to research potential purchases before letting a gun shop sell you something that won’t meet your needs, sound and or back pressure wise.

 

[ronsatspokane]

I've been thinking about building a dedicated suppressor gas gun. In talking to those who have been down this path, one method to minimize gas in the face is a variable gas block. Tune the block to the point that it cycles ok. Another is to buy a barrel that is designed to work with suppressors. Essentially a smaller gas port. Lot of variables to play with though. If you are doing an SBR suppressed gas gun then you are talking about a carbine length gas system and they are finicky. I'd make sure that you address the gas issue first then start tuning by trying different buffer weights until you get reliable cycling. I think that once you build one it will be kind of useless without the suppressor installed.

 

[rickiesrevenge]

Another option is to use a larger bore can. For example use a 30 cal can on a 223.

 

[GotRDid]

Brilliant advice in previous posts!
Some of the newer “Flow Through” cans like Huxwrx help in this area.

 

[AccelR8]

My experiences:

I shoot a Harvester 300 on a 223/5.56 AR15 carbine with a 16” barrel. I put on a Silencerco Alpha brake/suppressor mount. Originally I used direct thread but I didn’t like having to wrench off the flash hider to thread on the suppressor. But the brake alone with no suppressor is loud and even with hearing protection shooting at the range from a covered position, I’ll get a headache after a while. I recently put another carbine together and used a three prong FH/Alpha mount on that one to avoid the concussion (yeah I know it’s only a 223) when shooting without the suppressor.

I use an adjustable gas block and I can turn the gas up and down as needed, can even shut it off. Even so there is enough blow back the get the insides of the upper and lower receivers dirty. Just have to clean up more frequently.

I had a reduced power hammer and trigger spring set. I used to run my BCG with an amount of CLP lube that many shooters would say is too much. I did so because it prevented the hard carbon buildup on the bolt tail and inside the carrier. Made clean up so much easier. But one time after firing a lot of rounds suppressed I got a misfire or two...click but no bang. Light primer indent. Took apart the BCG and inside around the firing pin was a heavy sludge, a slurry of oil and blow-back crud. Cleaned it all up and went back to a regular power hammer spring, problem solved. I never had that trouble shooting un-suppressed so, yeah back pressure/blow back.

I really don’t notice gas blow back in my face. Always wear eye protection though.

So in conclusion...adjustable gas block, clean various parts frequently, if you’re going with a quick-attach mount I’d advise don’t use a brake style mount because a. 223 doesn’t have much recoil or muzzle rise and b. it’s going to be LOUD especially with a short barrel when not suppressed and probably pretty flashy too.

I think for an AR SBR, 300 BLK is better suited in that role than 223/5.56. Don't know what chambering you are going with but just throwing that out there.

 

[AccelR8]

Guys used to use RTV silicone sealant on the charging handle. De-oil the CH so the sealer sticks to it, apply some kind of release agent to the upper receiver so the sealer doesn't stick to it, then fill the gap between the upper and the CH with the sealer. smooth it off so it looks nice and let it dry. I've never done that so I can't say but guys who did said it cut down on the gas to the face.

There used to be a plug you could buy that went in place of the forward assist assy. that acted as a vent, directing gas down and away. I don't know if you can still get those. I've never felt the need for one. Of course it eliminates the forward assist function.

 

[troupe]

If you are building your rifle, a piston AR shorty setup helps over a gas impingement system. Cleaner and cooler (Temp) on the bolt system.

 

[TimS]

I use an adjustable gas block to minimize the fouling in the receiver

 

[Cecil S.]

Thank you all for your replies its great information from real shooters. I have done my homework and researched for days. But I wanted to hear from the members here to get "the real deal" before i purchase. I will be shooting a CMMG 10mm with an 8" barrel and while subsonic dosent really get my blood flowing I might play around a little, full power 10mm makes me smile and what is rough in a hand gun becomes manageable in a carbine. My main concern was shooting clean as possible.

 

[Cecil S.]

My experiences:

I shoot a Harvester 300 on a 223/5.56 AR15 carbine with a 16” barrel. I put on a Silencerco Alpha brake/suppressor mount. Originally I used direct thread but I didn’t like having to wrench off the flash hider to thread on the suppressor. But the brake alone with no suppressor is loud and even with hearing protection shooting at the range from a covered position, I’ll get a headache after a while. I recently put another carbine together and used a three prong FH/Alpha mount on that one to avoid the concussion (yeah I know it’s only a 223) when shooting without the suppressor.

I use an adjustable gas block and I can turn the gas up and down as needed, can even shut it off. Even so there is enough blow back the get the insides of the upper and lower receivers dirty. Just have to clean up more frequently.

I had a reduced power hammer and trigger spring set. I used to run my BCG with an amount of CLP lube that many shooters would say is too much. I did so because it prevented the hard carbon buildup on the bolt tail and inside the carrier. Made clean up so much easier. But one time after firing a lot of rounds suppressed I got a misfire or two...click but no bang. Light primer indent. Took apart the BCG and inside around the firing pin was a heavy sludge, a slurry of oil and blow-back crud. Cleaned it all up and went back to a regular power hammer spring, problem solved. I never had that trouble shooting un-suppressed so, yeah back pressure/blow back.

I really don’t notice gas blow back in my face. Always wear eye protection though.

So in conclusion...adjustable gas block, clean various parts frequently, if you’re going with a quick-attach mount I’d advise don’t use a brake style mount because a. 223 doesn’t have much recoil or muzzle rise and b. it’s going to be LOUD especially with a short barrel when not suppressed and probably pretty flashy too.

I think for an AR SBR, 300 BLK is better suited in that role than 223/5.56. Don't know what chambering you are going with but just throwing that out there.

I may be way wrong here but the burn rate of powder and bullet weight is a big concern with the AR style gun. If i understand correctly the heavier bullets allow for a cleaner burn if the powder is matched correctly. Let not forget I still consider myself a NEWBIE.

 

[troupe]

I shot one of the CMMG in 10mm. It was a very good shooting AR style pistol. The way the CMMG has a slight delay unlocking in their bolt design, I can not say how it will affect the unlocking, if at all. Great little pistol.

 

[Cecil S.]

I shot one of the CMMG in 10mm. It was a very good shooting AR style pistol. The way the CMMG has a slight delay unlocking in their bolt design, I can not say how it will affect the unlocking, if at all. Great little pistol.

My concern is back pressure on the delayed blow back with loads i want to shoot. But I may be way over thinking this so I will take a shot and dive in. I am set to play with powder load and bullet speed this should be fun.

 

[troupe]

My 9mm is fine in the blowback, only dirty. Granted it is not a 10mm delayed. Good luck and want to hear how it works out.

 

[Cecil S.]

My 9mm is fine in the blowback, only dirty. Granted it is not a 10mm delayed. Good luck and want to hear how it works out.

maybe look into the powder you are burning lots of answers there. are you shooting suppressed?

 

[Knotwild]

PewPew Tactical review does not mention any blow back on the CMMG 10mm. I personally would shoot it a as lightly lubed as is possible, reliable, and protective of the gun. Oil and grease gathers stuff and some remaining gas might blow it back in your face.

The CMMG delayed blowback system does not use a gas tube, so you won't be blowing gas back against the bolt and dumping it inside your receiver. With a suppressor that has ample volume and a good baffle design, you shouldn't have a minutes problem. Some low pressure gas may come back, but I have no experience with the CMMG, so I don't know.

As far as a suppressor goes, you are going to be limited to something that can handle 10mm and up and that can disassembled for cleaning.

How CMMG Radial Delay System Works

Pew Pew 10mm Review

I built a 300 SBR, and bought a 45acp straight blow back AR (that was a total disaster and returned for refund). Neither impresses me even a little bit for the type shooting I do, and was therefore a waste of time and money. But I have to admit that the 45 with a Hybrid 46 was amazingly quiet.

So good luck.

 

[Coyotefurharvester]

I have been using One shot cleaner and lube on my bcg and upper/lower surfaces. Still see crude in the trigger, so I remove and clean occasionally. But the rest seems to clean/wipe off easy.