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Suppressors Done it all, AR still filthy when suppressed

Arctic Cowboy

Arctic Cowboy

Novice shooter, expert bullshitter
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Full Member
Minuteman
Jul 13, 2013
153
35
Wasilla, AK
Okay so I’ve tried to do my research and I’ve pretty much done everything that’s been suggested to fix the problem with no luck.

I’ve got a DI AR in .223wylde with 14.5” barrel that I run a SiCo Omega can on. I’ve got the tuneable gas block turned down to bare minimum function with no can, I’ve got the bootlegger adjustable BCG, and the Griffin Armament charging handle.

I run about 150-200rnds of PMC before the system is so gummed up it won’t function. The top 2” of the mag is coated with shit along with the top 6 rounds or so. The grime cleans off easily enough but I don’t want to have to strip and clean my rifle every 150 rounds to keep it functioning.

I’d like to swap to a piston kit but I’ve heard some horror stories and it’ll really restrict how I set the rifle up, so that’s the last resort for me.

Anything else I can try?

Note* I do have a TBAC ultra 9 coming that I plan on running but seriously doubt it’ll help anything.
 
Why are you tuning your gas block without the suppressor? You are going to have too much gas with the suppressor on.
 
Incase I have to shoot it unsuppressed. Its not a dedicated suppressed gun and I don’t want a single shot if I can’t run a can for whatever reason
 
Do you have carbine gas or mid-length?

Carbine gas has too much dwell in a 14.5" barrel, adding a can will give it way too much dwell and blow lots of crap in to the upper.

Mid-length will have less dwell, certainly a move in the right direction.

I'm not sure there is going to be any setup that runs without a can and runs clean with a can on the same gas setting.

You might want to look in to a Noveske switch block so you can have two settings. I think the POF dictator gas block might do the same thing too.

I think the nature of a can might cause it to retain pressure until after extraction and pump GSR in to the upper back through the chamber. If that's true, the only way to keep it clean is to delay the bolt unlock.
 
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It’s a carbine length gas system. I’ve looked into the switchblock, but my dumbass pinned and welded the ASR on which means I’m stuck with it for now. Changing it to an sbr nfa is in my near future though. Is there a way to change a carbine to a midlength without swapping barrels?
 
Oh and the bcg I have is adjustable similar to a gas block but doesn’t seem to help at all
 
Arctic Cowboy said:
It’s a carbine length gas system. I’ve looked into the switchblock, but my dumbass pinned and welded the ASR on which means I’m stuck with it for now. Changing it to an sbr nfa is in my near future though. Is there a way to change a carbine to a midlength without swapping barrels?
Click to expand...
No.
 
You either tune it run suppressed and keep the grime to a minimum (but not eliminate) or you tune it to run unsuppressed and it will be a dirty mess. You can not have both.
You have to think about what the fuck is going on in the gun. Without a suppressor a semi-auto gun has to be timed to cycle at just the right moment. In general with the tip of the bullet just leaving the barrel the bolt should just start to unlock, it could delay until the base of the bullet just about to exit the barrel but the point is timing is important. If the bullet leaves the barrel, then all the pressure will escape out the muzzle and there wont be enough to cycle the bolt/carrier.

Someone might get on as say high speed cameras show the bullet is 5/16" past the muzzle, that is fine, it would take time for all pressure to be lost. The point is the bullet is not even 2 inches down range when the bolt is open.

When you add a suppressor you have lengthened the barrel. the bullet is 15 inches from the chamber (on your 14.5" barrel) but it is still inside the suppressor when the bolt opens. You now have a tube (the barrel) filled with gas under pressure when the case is removed from the chamber, (at which point the bullet is 2-3 inches past the muzzle but still a cork inside the suppressor) since the gas and pressure can not exit out the front it exits out the chamber into your face.

When you tune the gun for a suppressor, you are trying to time the action opening to the bullet leaving the suppressor, this is why unsuppressed the the gun becomes a single shot, the action is trying to work when the bullet is 6 inches down range, the pressure is gone.

This is where you need a gas block that has detents. Tune it for suppressed by closing the gas block all the way and then one shot at a time open one detent at a time until the bolt locks back on an empty mag. (then personally open one more click) write that number down, remove the suppressor and open the gas block until the gun functions again. write that number down, might be something like 14 clicks suppressed, 22 clicks unsuppressed. THEN when you switch from suppressed to unsuppressed you will know you need to open or close the gas block 8 clicks (or what ever number you come up with).

This is where gas blocks like the Noveske switch block are great in that it just has 2 settings, suppressed and unsuppressed. just flip from one to the other, also my original Ruger SR15 has a 4 position block, 4 is max gas for really dirty gun (never had to use that) 3 normal gas, 2 suppressed, 1 no gas, (Noveske has an off position as well). I can tell you that with both those if you don't adjust the gas block you know it the first shot. One way you get a face full of gas the first shot, the other way there is no 2nd shot (action did not cycle). So the difference is not slight, it is huge.
 
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I always knew they’d run dirtier, just figured I’d get more than 150 rounds before it begins to fail. I’ll tune it down to suppressed while I figure out what my game plan is.
 
Travclem said:
Dirty ARs are just part of the deal when running suppressed. I have never had an issue with any quality (LMT, BCM, DD, Larue, Colt, etc.) gun running dirty.
Click to expand...
YEP!!!
Suppressors are dirty no matter what you can minimize it but you can not eliminate it. I have never had a gun quit from suppressor grime, even before I understood tuning.
 
I’m surprised yours goes T/A after 150 rounds? My SPR is a dirty girl who doesn’t get the cleaning attention she deserves. I’ve run shitloads of rounds through it without cleaning. The smoo fortunately doesn’t slow mine down.
I added a bootleg adjustable carrier just so I could tune down the bcg speed when adding a suppressor.
 
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I have a 16” midlength BCM with H-buffer that I run with or without a can. Dirty with a can, puts all kinds of crap into the mag but I’ve never had failures.

Out of curiosity, what do you use for lube? I used to use slip2000 (it was fine) and have switched to a calcium sulfonate grease after a bunch of research. I’m guessing you may have a lube issue.
 
No way to change gas system length except possibly cutting down a 20"+ hbar to an SBR.

The good news is Faxon Firearms makes an 11.5" barrel with mid-length gas and it isn't terribly expensive, probably not much more than the cost of cutting and threading your current barrel so swapping makes a lot of sense even if you could cut it.

If you're going to regulate gas, you should do it at the gas block, that will reduce the amount of gas dumped in to your upper after the gas key has moved back off the gas tube. An adjustable gas key has no way to do that.

I think the Faxon barrel was kind of designed for running suppressed so there are probably many examples out there that you could learn from to see what works.

What you have now is just about a worst case scenario.
 
One more thing, my favorite cheap 5.56 ammo is PMC X-TAC green tip. I don't have a suppressor but it seems to run cleaner than all of the XM193 and XM855 I've tried. It's a bit more expensive than PMC Bronze 55 grain but worth it to me.

I've never tried it but I've heard the dirtiest stuff out there is Wolf polymer coated steel case ammo.

It can't hurt to find ammo that burns cleanly and completely.
 
Just an assumption, but your failure at such a low round count is odd. You might be in a weird spot with too much gas to run clean, but not enough gas to run while dirty. Try swapping one part at a time, regular bcg, open up the GB, inspect the buffer and spring.

I'm currently going 800-1000 rounds between cleaning with an ultra 7 on a stock 16" upper with only an h3 buffer and a plus power spring.
 
SDet said:
Just an assumption, but your failure at such a low round count is odd. You might be in a weird spot with too much gas to run clean, but not enough gas to run while dirty. Try swapping one part at a time, regular bcg, open up the GB, inspect the buffer and spring.

I'm currently going 800-1000 rounds between cleaning with an ultra 7 on a stock 16" upper with only an h3 buffer and a plus power spring.
Click to expand...

I do NOT recommend opening up the gas block. He has too much gas in a carbine gas system in that barrel length.

OP, you can always grind the weld and pull out the pin on the flash hider, not a big deal really. I’d personally do an adjustable gas block or a new barrel, although I think you should grease that bolt and carrier rails to see if that fixes the early failure problem. Regardless of the overgassing, you shouldn’t have issues that fast.

I haven’t gone past 1k without cleaning, but at 1k I’m having zero issues.
 
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Dirty8404 said:
I do NOT recommend opening up the gas block. He has too much gas in a carbine gas system in that barrel length.

OP, you can always grind the weld and pull out the pin on the flash hider, not a big deal really. I’d personally do an adjustable gas block or a new barrel, although I think you should grease that bolt and carrier rails to see if that fixes the early failure problem. Regardless of the overgassing, you shouldn’t have issues that fast.

I haven’t gone past 1k without cleaning, but at 1k I’m having zero issues.
Click to expand...
He said he has an adjustable gas block. Depending on the stoppage, a few clicks open could increase reliability.
 
No, he has an adjustable carrier and a standard gas block he can't change because his muzzle device is pinned.
 
Before you add or swap parts, try lubricating more than you currently are. Something thick like slip2000 ewl 30 if your in a hot environment or enough normal slip that the bolt looks wet all over.

Other lubes work too as long as they don’t burn off fast as hell. When in doubt, add lube.

A mk18 and surefire socom is a over gassed lil bitch but it runs when you keep it wet.
 
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I also run suppressed 16in carbine setup with pmc 55gr bronze.
On hot and mild days no problems for 200 rds, sometimes don't clean between weekends.
Have been accused of over lubing many times, so I try and dial that back.

My problem came in mild freezing temps with the gunk jamming up the chamber.
First round only.

A quick run of the bore snake got it fuctionable .

Bore snake and bolt wipe, 3 minutes?
I have also added 2 tungsten weights in my buffer, no other mods.
Runs suppressed or not no agb.

You can diy the h2 buffer cheap.
 
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Arctic Cowboy said:
I always knew they’d run dirtier, just figured I’d get more than 150 rounds before it begins to fail. I’ll tune it down to suppressed while I figure out what my game plan is.
Click to expand...

CLP squirt on the bcg is your friend when running suppressed dirty. They dont fail on me if you keep it wet. Run it dry and all kinds of issues.
 
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I used to use Slip 2000 and CLP (nothing wrong with them) but I really think grease (specifically calcium sulfinate) is the way to go.

The AR15/M4 is an unsealed machine that slides, no different than parts on a hay baler or a dozer that are greased.

Calcium Sulfonate is a food-grade base, high water-washout resistance, high temp, pressure, and naturally anti-corrosive (Li-base greases need additives). Plus grease seems to self-clean a sliding surface, migrating debris toward the low shear areas.

My rifle gets lubed after cleaning and not again until I clean. I’m at ~300rds now, I should run it without lubing until it fails.

EDIT: want to add, I only shoot this rifle suppressed.
 
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Thanks for the input guys, so to clear up the setup, I have the Odin tuneable GB and a Bootleg adjustable BCG.

I do use slip 2000 but am typically on the lighter side of useage. I’ll dial it up some and see if that helps. I live in AK So a screaming hot day for us is 85.

I’m gonna grind off the asr and throw the upper on a pistol lower while I wait for my NFA. I’ll start swapping out GB, BCG, buffers, etc to see if I can’t figure out what the weak link is. I’ll most likely swap over to the mid length faxon barrel suggested earlier. Worst case is I totally scrap this idea and turn it into a predator gun and build a piston rig from scratch.
 
Arctic Cowboy said:
Thanks for the input guys, so to clear up the setup, I have the Odin tuneable GB and a Bootleg adjustable BCG.

I do use slip 2000 but am typically on the lighter side of useage. I’ll dial it up some and see if that helps. I live in AK So a screaming hot day for us is 85.

I’m gonna grind off the asr and throw the upper on a pistol lower while I wait for my NFA. I’ll start swapping out GB, BCG, buffers, etc to see if I can’t figure out what the weak link is. I’ll most likely swap over to the mid length faxon barrel suggested earlier. Worst case is I totally scrap this idea and turn it into a predator gun and build a piston rig from scratch.
Click to expand...

If you had planned on running suppressed and unsuppressed you should have gotten the Odin Works adjustable gas block. I have 5-6 clicks (20 clicks total adjustability) between my suppressed and unsuppressed settings.

https://www.odinworks.com/Adjustable_Gas_Block_p/gb-adj.htm

It's an unfortunate naming convention they used, but the "tunable" version is really only adjustable one time.
 
Thinking about this more, ditch the adjustable bolt carrier or gas key.

It can slow down unlock but doesn't control the amount of gas in your upper so if it is adjusted to anything other than wide open, it just means you have to dump more gas in your upper.
 
I did not read all the replies.
I did read a few and the OP.
The answer is you have a perfect storm for a dirty, gummed up action.
Improvement can be made if you do the following.

Tune the gas block to the suppressor.
Get high quality ammo that runs clean.
Get a RLGS.

Only use bore snake as often as you reuse toilet paper. Same concept. Rubbing with dirty shit will not make things clean. It will just move it around. Good enough for some folks apparently. Not happing on my rifle or ass. The mere existence of a bore snake proves it is easier to spend money than think.

Cleaning an AR is a fact of life. Cleaning a suppressed AR is a frequent fact of life. Not so much the barrel as the BCG and action.
Otherwise, no fix will do much.
 
rth1800 said:
Get a RLGS.
Click to expand...
On a 14.5" barrel? I would have no hesitation with an intermediate 14.5", and I've successfully used a 16" rifle gas unsuppressed, but a 14.5" RLGS is really pushing it.
14.8_AGP_barrel_gas_block_tube.jpg

This is a 14.8" RLGS, as you can see it's only got around 1.5 inches of dwell time.
 
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Going to need a longer barrel for suppressed use of low quality ammo and long range trips. Some things are just not going to work.
 
I wonder if ammo quality is the offending component here, I've witnessed a few suppressed shorties run all day at matches and shoot well over 200 rounds with no signs of impending disaster. Dirty, but functioning just fine.
 
PMC is not too bad of ammo but uses cheap, dirty powder which is a problem with everything else tilted to cause trouble.
 
It doesn't matter what you do -- even piston ARs get filthy when shooting with a can. The can creates backpressure, fouling gets sucked into the receiver, it's a fact of life. Timing doesn't matter. A piston probably helps a bit but ultimately doesn't matter much. You just have to clean it and clean it often. If I have a weapon I'm shooting suppressed I use Fireclean. I know I know it's just cooking oil or whatever bs but it works. Pop that BCG out, wipe it clean, pop it back in -- BOOM. You're cooking with gas, err, vegetable oil.

I've found that as long as I keep the weapon hot it will continue to operate even badly fouled with suppressor gunk. If it gets a chance to cool down then it'll seize.
 
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Mooncake said:
It doesn't matter what you do -- even piston ARs get filthy when shooting with a can. The can creates backpressure, fouling gets sucked into the receiver, it's a fact of life. Timing doesn't matter. A piston probably helps a bit but ultimately doesn't matter much. You just have to clean it and clean it often. If I have a weapon I'm shooting suppressed I use Fireclean. I know I know it's just cooking oil or whatever bs but it works. Pop that BCG out, wipe it clean, pop it back in -- BOOM. You're cooking with gas, err, vegetable oil.

I've found that as long as I keep the weapon hot it will continue to operate even badly fouled with suppressor gunk. If it gets a chance to cool down then it'll seize.
Click to expand...

does it smell like french fries? :)
 
For the sake of data points
My 16" mid length with only an h3 buffer will go 1000 rounds between cleanings with minimal oiling.
I've also put 3000 rounds in a day on a suppressed 11.5 midlength that only runs suppressed with only oil in the bcg vents very 500 rounds or so. As far as suppressed ars, it runs pretty clean. No gas face or soot anywhere but the chamber.

It's possible, just have to find the right mix.
 
A lot of y’all are recommending lowering the amount of gas/dwell. “Just barely” functioning on suppressed is a recipient for failure with someone who is a light luber (don’t worry if it starts dripping out the seams, that’s not bad).

There’s a reason m4 rifles have carbine gas and big ports. When shit gets fouled and creeps towards shutting down, more gas is usually mo betta

The OP might just have to get used to dirty. If he’s a lefty, maybe look at some options to reroute that gas.
 
Many folks go with a heavier BCG and spring for this reason when running suppressed. Basically you need to add a little weight\force to slam through any accumulated grime.
 
In the field a quick rip with a preped bore snake doesn't slow you down much between stages.
By the way you can wash your bore snake with your dirty skiveys.
Or do you not clean them either.

Pmc does run dirty in any cal they sell, it is also very reliable and reasonably
accurate for the price for range ammo . Imo
Have had pmc finaly congeal in cold weather after shooting stopped, causing a problem
That a bore snake quickly fixed.
 
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Arctic Cowboy said:
Okay so I’ve tried to do my research and I’ve pretty much done everything that’s been suggested to fix the problem with no luck.

I’ve got a DI AR in .223wylde with 14.5” barrel that I run a SiCo Omega can on. I’ve got the tuneable gas block turned down to bare minimum function with no can, I’ve got the bootlegger adjustable BCG, and the Griffin Armament charging handle.

I run about 150-200rnds of PMC before the system is so gummed up it won’t function. The top 2” of the mag is coated with shit along with the top 6 rounds or so. The grime cleans off easily enough but I don’t want to have to strip and clean my rifle every 150 rounds to keep it functioning.

I’d like to swap to a piston kit but I’ve heard some horror stories and it’ll really restrict how I set the rifle up, so that’s the last resort for me.

Anything else I can try?

Note* I do have a TBAC ultra 9 coming that I plan on running but seriously doubt it’ll help anything.
Click to expand...
 
I have found that Fiocchi ammo runs cleaner than PMC in my suppressed LWRC 8.5" SBR. It's a piston system, but it still has a bit of blowback through the magwell and eject port. Dirtiest is Winchester white box, then PMC, then military ball. The Fiocchi is almost as clean as my Varget reloads.
 
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Suppriesed wwb works, got tired of primer strikes and stovepipes with that.
Winchester should be ashamed of white box.
 
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My LWRC SBR eats everything and it doesn't have an adjustable gas block! I believe that it doesn't necessarily "eject", rather it "pukes" WWB and PMC. They are both filthy rounds.
 
Arctic Cowboy said:
Okay so I’ve tried to do my research and I’ve pretty much done everything that’s been suggested to fix the problem with no luck.

I’ve got a DI AR in .223wylde with 14.5” barrel that I run a SiCo Omega can on. I’ve got the tuneable gas block turned down to bare minimum function with no can, I’ve got the bootlegger adjustable BCG, and the Griffin Armament charging handle.

I run about 150-200rnds of PMC before the system is so gummed up it won’t function. The top 2” of the mag is coated with shit along with the top 6 rounds or so. The grime cleans off easily enough but I don’t want to have to strip and clean my rifle every 150 rounds to keep it functioning.

I’d like to swap to a piston kit but I’ve heard some horror stories and it’ll really restrict how I set the rifle up, so that’s the last resort for me.

Anything else I can try?

Note* I do have a TBAC ultra 9 coming that I plan on running but seriously doubt it’ll help anything.
Click to expand...

I don't like the bootlegger BCG, it can't take fast aimed fire or burst fire or Fostech fire. The original Gemtechs work for me in the suppressed setting, in the non-suppressed setting they suck and I put in a Ni-Bo or TiN slippery bolt carrier.
The other guy is right... 5.56, .223 wylde or normal... barrel length of your choosing... they all get filthy.
Finish your mags so you don't have dirty ammo in them and just hose your gun out with NAPA or any other auto parts store Non-Chlorinated brake or parts cleaner. Be sure it's the non chlorinated one, it looks like the Chlorinated one but chlorine will discolor and/or melt plastics and may ruin your aluminum. We overused Clorox during the beginning of the AIDS crisis on the ambulance and it ruined vinyl and aluminum. NAPA stuff $3.00 a can or often two for $5 even in Alaska, Birchwood Casey Gun Scrubber and Remington Gun Cleaner and whoever makes Crud Cutter all cost from $11.00 to $18.00 for the big cans. Read the labels, they are all the same basic ingredients. It's like buying Walmart's generic acetaminophen versus genuine Tylenol... you pay three or four times as much for less Tylenol.

I can shoot 500+ rounds in an afternoon, I guess I could try for a full case some day, and my AR's keep functioning. Sometimes if I have it I'll spray RemOil in the barrel lugs and hose down the BCG while its in the gun, you can get at the engagement lugs, the side and the bottom easily. Some of the lube on the side will leak down around the back if you lube the carrier with the gun flat on the table or ground and the carrier showing through the ejection port cover...

Maybe switch out the bootlegger?
 
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There's another problem I've had with suppressed AR's is with the empty case or live round jamming in the chamber and the bolt getting seized. I've had to then drop the mag and stick a screw driver under the bolt through the magwell and jimmy it open.

Also there's the problem of all that gas coming in your eye through the charging handle when suppressed. It's unsafe to shoot it without glasses as everytime my eyes get blasted with grit/soot from the charging handle

I think the AR is just not a good host for a suppressor with its "shits where it eats mechanism". Even an AK is better.

I think if you need to use an AR type, then the POF with its gas piston and chamber cut outs is better.
 
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veeramani said:
There's another problem I've had with suppressed AR's is with the empty case or live round jamming in the chamber and the bolt getting seized. I've had to then drop the mag and stick a screw driver under the bolt through the magwell and jimmy it open.

Also there's the problem of all that gas coming in your eye through the charging handle when suppressed. It's unsafe to shoot it without glasses as everytime my eyes get blasted with grit/soot from the charging handle

I think the AR is just not a good host for a suppressor with its "shits where it eats mechanism". Even an AK is better.

I think if you need to use an AR type, then the POF with its gas piston and chamber cut outs is better.
Click to expand...

After seeing most of these replies I’m very seriously considering the AA or superlative arms Piston kit (not sure I want to shell out for the Pof just yet). I’m gonna swap a few parts around just Incase there’s something flukey, but if that fails it looks like I’ll be going to the dark side and doing a piston.
 
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