First time shooting suppressed

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dpollard

New member
I am not sure if this needs to go in this forum or over on ARs but I have a question about shooting a suppressed AR...

Finally got my first can after an 8 month wait, shorter than I anticipated so I was happpy because I waited 11 months for my SBR stamp. Went out and shot it today with my sub-sonic 300 blackout SBR, 10.5" barrel. Gun cycled flawlessly but I did notice the ejected casings had a lot more fowling on them than when not shooting suppressed. They were almost sticky to the touch. I assume this is from gasses blowing back due to the can...is this normal and to be expected or do I need to make adjustments somewhere (more or less powder, different powder, adjustable gas block)?

On a different note, even shooting subsonic loads it was louder than I would have guessed.
 
Shooting suppressed is very dirty, your brass, magazine, bolt, and everything thing else gets dirty as heck. As far as how loud it was its because of the bolt opening and some of the sound exiting out the side, bolt guns are much quieter
 
You're not kidding. I couldn't believe it. My mag follower was very dirty! Sounds like I shouldn't be worried about the fowling.
 
I got my Omega stamp last August and I discovered the same thing you did, suppressed guns are very dirty. It's totally worth it IMO but yes they are dirty. I don't mind the dirt but I have had some increase in failures to eject (ripping the rim off the case) and increased difficulty in ejecting unspent rounds. I clean the chamber more often now and I am considering switching barrels because I had some of these problems before the can with my RRA barrel but it has gotten worse. I'm hesitant to replace it because it is very light weight and very accurate. I'm shooting handloads so the failures could be my fault. I'm tempted to try a new barrel that is nitride coated since that should make things slicker?
 
You may be over gassed if you are ripping rims of your brass, with the rounds sticking your gun may have a little tighter chamber and you may need to adjust your sizing process. Shooting suppressed is very dirty wait till you see the last could rounds in a unfinished mag.
 
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I was definitely overgassed to start with (might still be) as it was chucking brass to 1:00 o'clock. I put a Superlative Arms adjustable gas block on it and ran it in the bleed off mode. Even with very reduced loads (40gr Vmax at 2200fps for coons) it would still cycle and that was turned ALL the way out. That put the brass back to 4:00 o'clock. To be fair though, I have ripped rims off and had other stuck case issues before I had a can so I'm guessing that I just have a sticky chamber. I may also need to crank down my neck sizing die? I think I'll try a new barrel since I want to swap handguards anyway.
 
I haven't had any rims ripped off. Just dirty brass and mag follower. I did convert all of my brass from 223 and learned the hard way case mouth cannot exceed .012", especially in my barrel, which has a tight chamber (Odin Works). I do get a round every once in a while that won't chamber and won't extract without doing the "pogo" method (slam buttstock on table while ripping back the charging handle).
 
Originally Posted By: 1badsheeNot sure I read that right, you are neck sizing only?

No, sorry it was late when I posted that, I'm using a full length sizing die.
 
No worries. The AR-15 is a gas operated, direct impingement firearm. So adding back pressure from a suppressor causes a lot more gas to exhaust back into the gun/chamber. You don't see it as bad as on a bolt gun. It is 100% normal and nothing to worry about.

As far as sound, they are louder than most people expect.
 
Trying to use ejection patterns to determine if your AR is over gassed is an exercise in futility.

If the AR has an adjustable gas block, the best method is to close off the gas until the AR will eject the last round but not lock back, then open it one click or about a quarter turn until it will just eject and lock back. Then shoot it enough to verify the setting. Use an H2, A5H2 our rifle buffer, depending on what RE your AR has.

If your AR does not have an adjustable gas block, you'll have to rely on feeling how hard the buffer hits. If the buffer does more than just kiss the RE using one of the buffers above, your AR is over gassed. It will need either an adjustable gas block or a BRT micro port or a barrel with the right sized gas port.
 


I spray mine with CLR before I start shooting make clean up easier.
I drilled a gas port hole in my charging handle.
Easy to do in a drill press or you can buy one.
 
Fouling is just part of shooting a suppressed AR, just have to clean more often.

Loudness can be changed. #1 is your can...they definitely don’t all sound the same, especially on an AR...try running someone else’s can with your best sounding round on your rifle, if it sounds better, admit to yourself you wasted a lot of time and money on the wrong can and either live with it or use it as an excuse to get another one.

If you don’t reload then #2 would be to get an adjustable gas block and adjust like mistwolf suggested, and #3 modify or buy a charging handle made for shooting suppressed.

If you reload then #2 would be powder selection. For something like 300 blk start at the top end of subsonic and drop your powder charge down as low as you can (with the appropriate powder) and still get lrbho every time. If you do it this way there really isn’t a need for an adjustable gas block.

Also consider seating your bullets as deep as you can without losing accuracy or getting over pressure signs. Deeper seating will build more pressure with less powder, more pressure gives better chance or lrbho, and less powder is normally quieter.

Certain powders can be noticeably quieter in different guns and actions. 4227 was noticeably quieter than several other powders in 300 blk running the same bullet at the same col at 1050 FPS in a bolt gun, but getting lrbho with 300 blk subs in an AR is noticeably quieter with 1680 than 4227.
 
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