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Suppressors Gassers and suppressors....

JRose

JRose

Gunny Sergeant
Full Member
Minuteman
Jul 10, 2007
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Ever since I started shooting my DPMS LR308 through a can, it stove pipes pretty regularly. The rifle used to run reliably, so I'm wondering what's going on?

I don't have any experience with suppressors, but have heard of adjustable gas blocks and such. Is this what I need to look into?
 
Re: Gassers and suppressors....

Before you drop the money on an adjustable gas block, try putting a heavier spring and buffer in it. If you can put some weight in the carrier then do that as well. If you put the heavier stuff in it it may not run without the can, but will stop problems with it. THe adjustable gas block will cut the gas back when shooting suppressed and then you cna crack it back up the other way when not suppressed.
 
Re: Gassers and suppressors....

It has a Tubb CS spring in it, stock buffer. I'll look into that.
 
Re: Gassers and suppressors....

I agree with Perryguy, give the man. a call. I've run a suppressor on my Armalite AR10 for several years now, no problems at all. I even had an adjustable gas block put on "just in case" right before I got the suppressor. I've left the gas block open 100% of the time, never had adjust anything.
 
Re: Gassers and suppressors....

+1 to everyones comments. Call the can manufacturer, they should know best. Some else has most likely had the same issue and you get sound advice on silencer talk
 
Re: Gassers and suppressors....

Typically a stovepipe means not enough gas. Suppressors add MORE gas pressure. Very odd. I would suspect your extractor is slipping.
 
Re: Gassers and suppressors....

Not much help I'm sure, but I had the same problem with my DPMS SASS. I have the same stove-pipe issues. I even got one case jammed BACKWARDS in the chamber! I called DPMS though and they had me send the rifle in for them to look at. I don't know how it turned out though because right after I sent it in, I came back to Afghanistan...
 
Re: Gassers and suppressors....

Sorry, missed this thread for a while...


It's a SAS can

Micro: it's not the typical stovepipe... It's like the case is not getting ejected all the way before the bolt goes forward again. Sometimes, a spent case will get jammed on the next round in the mag as well.

Fastford: I'm not sure which part your asking about, but if your talking about the can, I run it dry. As far as the rifle, usually just have a light coat of Break Free on the BCG.

Dusty: Nope, stock 18" barrel
 
Re: Gassers and suppressors....

It is short stroking. This is usually caused by low power rounds, dirty/clogged gas tube, dirty bolt/carrier, atc.

As has been stated above, and can will not reduce the gas pressure. It will sustain it at a lower leve beyond where an unsuppressed barrel drops pressure (i.e. after the bullet leaves the barrel).

What may be happening is the sustained pressure adds to the crap injected into your receiver - do a real thorough cleaning. try a grease instead of light oil on the bolt carrier.

Pay attention to the gas tube and gas key on the bolt carrier (pipe cleaners are your friend). Make sure the gas rings have the gaps spaced.

BTW - did you get your barrel threaded? If so, the gunsmith may have damages the gas tube, misaligned the gas block with the hole (port) cut in the barrel, or let some debris into the gas system.
 
Re: Gassers and suppressors....

It was threaded from the factory. That makes sense seeing as after I shoot it, the rounds in the mag and BCG look like they are fucking dry and filthy!

I doubt it's a under pressure problem from low power rounds, seeing as my load for this thing is HOT. LOL

It might just need a thorough cleaning and a greased bolt. What grease do you recommend?
 
Re: Gassers and suppressors....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DustyJacket</div><div class="ubbcode-body">
BTW - did you get your barrel threaded? If so, the gunsmith may have damages the gas tube, misaligned the gas block with the hole (port) cut in the barrel, or let some debris into the gas system. </div></div>

Good point.... I am going to thread mine soon for a can... even the tiniest of chips could play hell in the gas tube..
 
Re: Gassers and suppressors....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JRose</div><div class="ubbcode-body">...What grease do you recommend? </div></div>

There is a way to start a fight!
smile.gif


There are many recommended, but I cannot recommend anything, because the grease I use is not made any more, nor is it recommended (teflon suspended in grease).

Lube her up

If these are handloads, and you did not shoot these loads before getting the can, you might have the wrong preassure curve for your gas port and system........ They can be hot and still not have enough pressure at the right time to operate the system. Sierra and perhaps some other loading manual have different recipes for gassers.

And make sure the gaps in the gas rings on the bolt are staggered. One every 120 degrees is the recommendation.
 
Re: Gassers and suppressors....

OK, thanks. I'm having the same problem with hand loads as well as factory ammo.

Guess I just have to mess with it.
 
Re: Gassers and suppressors....

JRose-
got a SR-25 that did the same thing with my can, shot well for a while then started jammin up, got a armalite sass and it cycles fine with a can, BUT it has the adj. gas block for supp., i use handloads in both guns. took both bolts apart to compare, my SASS has an o ring over the extractor spring and my SR doesn't, got ahold of knights and they told me that could very well be the prob. so i am waiting for the new spring and o ring, but i think i'm gonna try a heavier spring and buffer as well.
 
Re: Gassers and suppressors....

I don't think it would hurt for me to start with an adj gas block, but I'm seeing there is a lot more stuff I need to check.

Thanks for all the tips everybody!
 
Re: Gassers and suppressors....

Please post here when you find an adjustable gas block for a .308 - I wish I could find one. Of course I have a bull barrel which makes it worse.
 
Re: Gassers and suppressors....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JRose</div><div class="ubbcode-body">Sorry, missed this thread for a while...


It's a SAS can

Micro: it's not the typical stovepipe... It's like the case is not getting ejected all the way before the bolt goes forward again. Sometimes, a spent case will get jammed on the next round in the mag as well.



</div></div>

Something similar happened to me on my RRA and an M4-2000 but my rifle was very dirty at the time.Not sure what the prob could be but does it do this w/o the can on as well?What do your primers look like on spent casings?
 
Re: Gassers and suppressors....

Dirty chamber.
Keep a good eye on your extractor wear.
Post a pic of the brass in the case head area.
 
Re: Gassers and suppressors....

I'll post some pics tomorrow... I broke the rifle down today and sho nuff, it's dirty as shit.
 
Re: Gassers and suppressors....

Expect to start having issues @ the 125-150 rds from a totally clean rife.
 
Re: Gassers and suppressors....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DustyJacket</div><div class="ubbcode-body">Please post here when you find an adjustable gas block for a .308 - I wish I could find one. Of course I have a bull barrel which makes it worse. </div></div>

I run a JP Rifles Adj Gas Block on my .308. Last time I talked to him he had them in stock. Mine is a medium contour bbl though. He's got them available for .750 and .936 barrels if that works for you.
 
Re: Gassers and suppressors....

Here's pics of the mess, I'm trying to dig through and find the spent cases now...

DSC_0400-4.jpg

DSC_0401-3.jpg

DSC_0402.jpg

DSC_0403.jpg
 
Re: Gassers and suppressors....

I might just leave the can off of it if it's gonna make that much of a mess.
 
Re: Gassers and suppressors....

That looks like the ammo out of every suppressed AR I've shot. They all get dirty like that but I never had jams in my .223.
 
Re: Gassers and suppressors....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Chuck Anderson</div><div class="ubbcode-body">That looks like the ammo out of every suppressed AR I've shot. They all get dirty like that but I never had jams in my .223. </div></div>

Yeah, the .308 seem to have issues. Not the .223


JP blocks just use a little set screw to adjust the pressure and the last i checked they were aluminum. Been known to blow out the set screw and not hold adjustment.
 
Re: Gassers and suppressors....

JRose, Bring it to Hardrock this weekend.

Mine get that dirty, both the 308 and 223, but both function very well filthier than that.
 
Re: Gassers and suppressors....

OK. I shot it the yesterday after a good cleaning, w/o the can, ran without a hiccup...
 
Re: Gassers and suppressors....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hooper</div><div class="ubbcode-body">
JP blocks just use a little set screw to adjust the pressure and the last i checked they were aluminum. Been known to blow out the set screw and not hold adjustment. </div></div>

JP makes Adj Gas blocks in aluminum and steel. I've been using them for over 10 years on a whole bunch of guns and have never had an issue with the aluminum blocks. I've also never had an issue with the adjustments. Once you adjust them and loctite them I've never had one move. Also once you get a few rounds down, carbon builds up behind the screw. If it was to adjust any direction it would be to open up and put more gas in the system, not less. Where did you hear they've been known to blow the screw out? That's a first for me.
 
Re: Gassers and suppressors....

I have a home made adjustable block on my LR308. No problems with the set screw backing out. I shot 3 shots w/out turning the gas down. The block is now open 3/4 turn from fully closed. I highly recommend an adjustable block when shooting a supressor.

The ONLY time my rifle will stovepipe is with a brass catcher on.
 
Re: Gassers and suppressors....

For what it's worth, after I opened up my gas port toward the high end of spec, I can shoot that sucker dry and dirty and it keeps working with no issues. I hadn't cleaned it since I got my SAS and put around 500 rounds through it and not a hiccup (was DIRTY). I run a Tubbs carrier weight and recoil spring and Teppo Jutsu gas block with a 24" T barrel. I do lube the bolt and carrier with grease after cleaning.
 
Re: Gassers and suppressors....

Break Free is not a lube. Neither is WD-40.

If you are going to run suppressed you either need to run it bone dry or greased and dry lubed. Dry lube is a fancy name for graphite, found in the local hardware store. Oil will just cook off.

Grease needs to go in the key wear spots. You will go a lot less before you need to clean it.

Don't worry. The dirty rounds in your mag will still shoot like clean ones....
 
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