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gas drum orifices plugged with brass/copper?

2K views 10 replies 4 participants last post by  Whole Bunches 
#1 ·
Hey guys - I run an L (SBR'd) suppressed with a 10.5" .300 blk upper. Round count is around 3000 -- 1500 supersonic 150 gr. Fiocchi and 1500 subsonic of various brands & bullet weights. The can is an Silcencerco Omega 300

My gas setting was 2 or 3 and gun ran reliably for two years, but I began to need to change gas settings often as they became sluggish and the gun became unreliable. So I took apart the adjustable gas block and discovered that 4 out of 7 ports were entirely plugged with what looked like brass but could also have been copper jacket.

I punched these out and assume that the gun will now be back to its old reliability. Can ya'll tell me if there's anything I can do besides routinely cleaning the ports to avoid this problem? Is it an ammo quality issue? I suspect the jacketing on some cheap S&B subsonics, but I'm not sure.

Thank you,
Matthew
 
#2 ·
I believe you answered your own question. ALL Suppressed firearms need more frequent cleaning. I think its because more carbon and copper/lead particles get blown back into the action. My Vector NFA Uzi suffers this same situation when shooting with the suppressor and subsonic 147's.
 
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#3 ·
Thanks for the feedback. Yeah, I agree I could stand to clean the internals more often -- although I would expect to see soot & carbon build up from gas backpressure, and not so much compacted jacket material (maybe I shouldn't be surprised?) I wonder which cartridges produce more jacket & case debris.
 
#4 · (Edited)
One of the reasons I went with a flow through can design (NG2 Defense or OSS...though I don't agree with how the latter treated the original owner and probably would never buy one from them for that reason).

No gas in the face, less fouling overall by a good margin. No having to clean my mags b/c they're full of crap either. No playing with the gas settings....just run it as you would without the can; no change in the cyclic rate. And still hearing safe. A little larger diameter though.

As for your specific issue....I'd wager the bbl port is oversized. Do you happen to know what size it is? Which type gas system do you have? I'm assuming it's a Type 3.

What happens on VEPR 12s (similar concept)...the larger port sizes shave larger pieces of jacket off the projectile and end up clogging the gas ports...except in the V12 it's melted/shaved shotgun wad.
 
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#5 · (Edited)
What happens on VEPR 12s (similar concept)...the larger port sizes shave larger pieces of jacket off the projectile and end up clogging the gas ports...except in the V12 it's melted/shaved shotgun wad.
Yea my Saiga 12's are horrible for this. Ive actually pulled the gas plug and had a ton of crap fall out.. Buffered shot is the worst.
I was using some plated 150's in my Honey Badger clone and had copper transfer back to the carrier. I was over the velocity threshold though pushing 1600 fps.
 
#6 ·
Yeah...my V12 usually has plastic wad melted to the puck. It's good for around 300 rounds or so before I need to clean it...otherwise, it will start malfing.
 
#10 ·
After thinking about this more...if it were solely an issue of port size, I'd likely have the issue too. Granted, I shoot a lot of bimetal in my XCRs....so maybe the harder outer jacket means it doesn't get shaved off by the port size....

I'm running .098" in some of my 5.56 XCRs IIRC. And after looking at this thread:

https://www.xcrforum.com/forum/15-field/12188-xcr-factory-custom-port-specs.html

I'm running a .116" port in the 7.62x39 with a 16" bbl.....so pretty freaking big.

I ONLY run bi metal in the x39....and I haven't seen the shaved projectile issue (granted, that's been a Type 1 gas block...swapping to a buried Type 3 on that gun in the near future when I pick up a new comp length upper).

The point I'm laboring to make is that I think you're right....it's probably the S&B ammo you mentioned.

Otherwise, I'd say just keep an eye on it. Turn up the gas as necessary and when you get to the last setting or next to last to make it run, time to break the dial down and take a look inside.
 
#11 ·
Had the copper/brass buildup in my 7.5” Blackout bbl type 3 gas system in a couple hundred rounds when new. Could no longer adjust the gas due to buildup. Got it all cleaned with a combination of filing off some of the buildup, soaking in copper bore solvent and poking a dental pick into the gas holes. No further problems.
 
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