Is this normal? Filthy brass w/ suppressor.

[MWM-5150]

Rifle:
Receivers & BCG: DPMS LR-308
Barrel: Rainier Arms- Ultramatch 308, 18", Mid-Gas
Gas Block: Syrac Ordnance- Click Adjustable .75"
Buffer: LR-308 Rifle Buffer (5.4 oz)
Recoil Spring: Tubbs Speeklock .308 Flatwire

To preface my main question, I've had issues with getting a good load worked up for this rifle since I put it together. It seems really picky about where I have the headspace set back on my brass in order to cycle reliably. A constant problem I had in the beginning was reloaded brass would not fully chamber. The bolt always seemed to stop about 1/8" from going fully into battery, then I would end up having to mortar the SOB to get the stuck brass out of the chamber. I mitigated a lot of this with a small base FL resizing die and making sure my headspace was set to 1.620" (max for best feeding reliability). Additionally, I was plagued with pierced primers and deformed case rims for a very long time. Installing the AGB, seemed to help with this a lot.

Anyway, suppressor got approved and received last April, and its been great. I have the adjustable gas block set up to run with the suppressor on (4 clicks from fully closed). This is the adjustment that was required for the bolt to lock back on an empty mag.

All this to say, the rifle seems to be cycling fine, but my God it just turns my brass to shit. Most of it looks like what is pictured below. The 5 pieces shown were from various loads of 4064 that I worked up trying to find a good recipe with this powder. This is not specific to 4064, a type of brass, or bullet. If Im using the can, it looks like this. So, is this normal? Or do I have something wrong? The chambering issues I had in the beginning led me to wonder if maybe my chamber was slightly out of spec, although I have no way of determining this without any HS gauges.

Any insight you could offer would be appreciated.

Edit: The brass pieces shown in the image appear to have varying degrees of filth. Each piece was taken from a different sample load. Lightest load is on the right, hottest on the left. I believe this batch ranged between 41-45gr of 4064.

 

[BearNaked]

mine look like that with a 223 bushmaster. i use 4064 as well and it looks like this with handloads or factory ammo. suppressors just shot a lot of the junk back into the gun and it looks just like that. one of the downfalls from shooting suppressed.

 

[MWM-5150]

mine look like that with a 223 bushmaster. i use 4064 as well and it looks like this with handloads or factory ammo. suppressors just shot a lot of the junk back into the gun and it looks just like that. one of the downfalls from shooting suppressed.

What's weird is using the same suppressor on my 223 AR they come out just as clean as they do without the suppressor on. I guess there is just less back pressure since its a .30cal suppressor.

 

[BearNaked]

What's weird is using the same suppressor on my 223 AR they come out just as clean as they do without the suppressor on. I guess there is just less back pressure since its a .30cal suppressor.

i run a 30 cal suppressor on my 223 so no telling. you are probably just getting a better seal in the chamber with your 223. on my bolt guns with the suppressor, it is only the necks that are smoked and the rest is still shiny. like i was saying, i put a lot of rounds through it and they produce awesome groups so im not all the worried about it. the only thing i need to do is get an AGB and then i am rocking and rolling.

 

[Servo93]

I run a 556 specwar on a 12.5" SBR and a 16" 6920, buddy runs an AEM5 on his Mk12 mod 1 and his Mk12 mod H clones. All of our brass is dirty like that. If you have a semi auto that ejects clean brass when suppressed you are lucky.
Running adjustable gas blocks or heavy buffers to delay the bolt unlocking will help with this, but it probably won't go away.

 

[ZombieMonkey]

Yep, that's the one big downside of a semi and a suppressor, they run dirty as shit. You can try to mitigate some of it with adjustable gas blocks, but as stated above you'll always be stuck with a degree of this.

 

[2ndamendfan]

That is absolutely normal. The bolt opens while there is still pressure in the barrel, due to the barrel technically being longer with the suppressor on. A heavier buffer and/or a adjustable gas block (which i see you have) can lessen it quite a bit. On many i see the gas block adjustment is not fine enough. 1 click makes to big of a difference and you just have to live with some gas coming out the back. My 300 BO is like that.

 

[TheGerman]

Oh yes.

I had a round in a mag in my SR15 that apparently always ended up having more rounds loaded ontop of it and lasted an entire training and range session in the mag while I used a suppressor the entire time.

When I went to unload the mag, the entire top half of the round was BLACK. I don't mean shaded a little darker, I mean BLACK.

Also have the Ops Inc can on my Mk12Mod1, and the brass shot through it is much dirtier coming out than anything not suppressed.

 

[WYO09]

Yep totally normal. Dirty as hell but i'll take it for the suppression I get. One issue I did run into is the grime caused some issues with one of my guns with a trigger tech trigger not working at times.

 

[csjavi]

That used to happen to me but not anymore These suppressors http://saimaastill.fi/portfolios/saimaa-still-supressor-quick-connection/ work like a charm. They are manufactured in Finland, but Arsenal is importing them into US.

 

[lennyo3034]

OP just out of curiosity, what suppressor are you running? Some suppressors have more back pressure than others.

 

[agbm]

Yes it's normal and there is a fix for dirty brass along with a dirty weapon Etc. https://osssuppressors.com
Baffles VS Baffleless
DI AR VS Gas Piston AR

 

[2ndamendfan]

That used to happen to me but not anymore These suppressors http://saimaastill.fi/portfolios/saimaa-still-supressor-quick-connection/ work like a charm. They are manufactured in Finland, but Arsenal is importing them into US.

I would like to see how and if they work. The blow back is not a "function" of the suppressor. But a by product of adding 6 inches (some smaller, some longer) of barrel length. The same thing would happen if you put a pistol or carbine length gas system on a 22 inch rifle (tuned for carbine or shorter barrel). Can you or could you get it to function perfectly with a suppressor? Yes but then it would be very undergassed when removed. So with that you have to have a "goldilocks" set up.

 

[MWM-5150]

Thanks for the responses, gentlemen. This makes me feel a little better. I just wanted to make sure something wasn't dangerous. As long as it functions well I suppose I shouldn't bitch. Most of the brass though, gets so beat up it may not be reloadable. I guess I'll limit my suppressed loads to brass that's towards the end of its usability anyway.

OP just out of curiosity, what suppressor are you running? Some suppressors have more back pressure than others.

Its an SAS 762 Stainless TOMB. Same as the Arbiter only made of 17-4 Stainless instead of Ti. I have the TOMB brake on all of my rifles and it works fantastically on all of them. The noise reduction is awesome. They advertise 35 db but I have no way of verifying that. All I'll say is I can shoot my 308 auto without ear protection and its not uncomfortable, bolt guns are even better. (typically I always wear ear pro, regardless if Im using the suppressor or not)

 

[Snuby642]

Shooting an aac can on a 300 blackout sbr heavyweight subs.
Mine shoots filthy, like a hog waller. After 100 rounds top to bottem and glad to here normal.
Thanks

 

[BearNaked]

Most of the brass though, gets so beat up it may not be reloadable. I guess I'll limit my suppressed loads to brass that's towards the end of its usability anyway.

if you are referring to the dirtiness of it then they are fine. just tumble them for a couple hours and they come back to life.

unless you are stepping on the necks after you fire them then there shouldnt be any reason they cannot be reloaded. i only shoot my ar suppressed and i really only shoot my reloads. no brass failures as of today with multiple reloads on it.

just like your jeans, they get dirty, you wash them. rip the crouch out, throw it away. same concept. they should be fine if all you have is some buildup on them.

 

[MWM-5150]

if you are referring to the dirtiness of it then they are fine. just tumble them for a couple hours and they come back to life.

unless you are stepping on the necks after you fire them then there shouldnt be any reason they cannot be reloaded. i only shoot my ar suppressed and i really only shoot my reloads. no brass failures as of today with multiple reloads on it.

just like your jeans, they get dirty, you wash them. rip the crouch out, throw it away. same concept. they should be fine if all you have is some buildup on them.

Normally I would agree with you but the bases are getting pretty chewed up too. Look at the case in the middle. That's not an optical illusion, its leaning a bit because the rim was bent during extraction.

 

[csjavi]

I would like to see how and if they work. The blow back is not a "function" of the suppressor. But a by product of adding 6 inches (some smaller, some longer) of barrel length. The same thing would happen if you put a pistol or carbine length gas system on a 22 inch rifle (tuned for carbine or shorter barrel). Can you or could you get it to function perfectly with a suppressor? Yes but then it would be very undergassed when removed. So with that you have to have a "goldilocks" set up.

I have had two suppressors on my Bushmaster Modular Carbine. The rifle functions fine without or with either suppressor with milder and hotter loads and different bullet weights. The rifle is in fact over-gassed. The brass got very dirty with the previous suppressor (Ase Utra SL5). When using the Saimaa Still suppressor, the brass looks just like brass shot without a suppressor. I have no idea how it works.

 

[BearNaked]

Normally I would agree with you but the bases are getting pretty chewed up too. Look at the case in the middle. That's not an optical illusion, its leaning a bit because the rim was bent during extraction.

agreed 100%. that one goes to the trash can. i wonder why your bases are getting jacked up?

 

[2ndamendfan]

Normally I would agree with you but the bases are getting pretty chewed up too. Look at the case in the middle. That's not an optical illusion, its leaning a bit because the rim was bent during extraction.

I have one gun that did that when a suppressor was added. Ruger SR-556. even with the gas on position 1 (suppressed). It looks to me it is trying to rip the rim off. Here is how I worked it out. In my mind the bolt was unlocking and trying to extract the case while there was still pressure pushing the brass against the chamber wall. It needed more time to let the pressure/gas escape and the brass to relax. I added buffer weight since I was on the lowest gas setting (new buffer from Heavy Buffers). Slowed the cycle time down a millisecond and problem solved.
Just food for thought.

 

[supercorndogs]

I ran a gas piston AR for a while. There was no way to slow down the timing in it, so it always blew a lot of gunk around the brass. I figured this out because at the same time I had a DI gun and I could make the brass come out clean by switching to my lower with a rifle buffer and tube[from a carbine and standard buffer]. I then further smoothed out the process with an adjustable gas block.

Bent rims are ofter a sign of over-gassing, unless its an FAL.

 

[MWM-5150]

I have one gun that did that when a suppressor was added. Ruger SR-556. even with the gas on position 1 (suppressed). It looks to me it is trying to rip the rim off. Here is how I worked it out. In my mind the bolt was unlocking and trying to extract the case while there was still pressure pushing the brass against the chamber wall. It needed more time to let the pressure/gas escape and the brass to relax. I added buffer weight since I was on the lowest gas setting (new buffer from Heavy Buffers). Slowed the cycle time down a millisecond and problem solved.
Just food for thought.

Adding a heavier buffer was going to be my next step, so that helps to hear. I thought maybe the spring change would help with this as well, but the difference it made was only noticeable in how the gun recoiled after re-tuning the gas block, but the brass looked the same.

 

[2ndamendfan]

I ran a gas piston AR for a while. There was no way to slow down the timing in it, so it always blew a lot of gunk around the brass. I figured this out because at the same time I had a DI gun and I could make the brass come out clean by switching to my lower with a rifle buffer and tube[from a carbine and standard buffer]. I then further smoothed out the process with an adjustable gas block.

Bent rims are ofter a sign of over-gassing, unless its an FAL.

The Ruger SR-556 is a piston gun with 3 settings on the gas block. Buffer weight is your adjustment in such a case.

 

[supercorndogs]

The Ruger SR-556 is a piston gun with 3 settings on the gas block. Buffer weight is your adjustment in such a case.

Mine was an Adams Arms gas piston. Adding buffer weight didn't do anything except make it short stroke worse. The only way I found to make it a little better was to increase the end play in the piston to the maximum amount suggested by Adams Arms. This gave just a little more time before the piston started acting on the carrier. Even when it would short stroke the brass would come out black.