gas drum orifices plugged with brass/copper?
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Thread: gas drum orifices plugged with brass/copper?

  1. #1
    Carbineman fivesidedpolygon's Avatar
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    gas drum orifices plugged with brass/copper?

    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
    "Oh, great... REAL bullets!" -Lucky Day

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    Marksman SSBiggun's Avatar
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    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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    Carbineman fivesidedpolygon's Avatar
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    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.
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    XCR Guru Sean K.'s Avatar
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    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.
    Last edited by Sean K.; 11-02-2019 at 04:08 PM.
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    Marksman SSBiggun's Avatar
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    Quote Originally Posted by Sean K. View Post
    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.
    Last edited by SSBiggun; Yesterday at 08:36 AM.
    A M16 is a fancy city girl, sexy as hell, but a bit moody. It's all good as long as you take her to the clubs and get what she asks. If you cross the? line, its over.

    An AK is a naughty girl, all in latex and with a whip begging you to be naughty. The nastier you are the happier she is. Its clear that she wont dump you, you'll have to do that on your own.
    The XCR is the perfect blend of both. Sexy as hell but willing to let you beat her and filthy her up and then beg for more.

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    XCR Guru Sean K.'s Avatar
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    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.
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

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    Carbineman fivesidedpolygon's Avatar
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    Quote Originally Posted by Sean K. View Post
    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.
    That’s good info. It seems to me, and I might be wrong, but 3-4 yrs ago when I bought my suppressor there wasn’t remotely as much marketing happening around flow-thru designed cans. If I had it to do over again...

    Jacket shaved off by the gas port is something I’d never seriously considered. My gas block is type 3 (2017 upper built by RA) I was aware of copper fouling in barrels and cleaning to protect against it, but since I hadn’t seen inordinate amounts of copper hiding in other places, I was pretty shocked to see that it was all getting hung up & compacted in the gas drum. I’ll check if the port is out of spec, but I don’t think so and i def don’t see a burr or anything in there. My pet theory is that it happened more rapidly with S&B 200 gr subsonic, because they had a brass-yellow plated jacket and the stuff I popped out of the orifices was brass colored. The problem developed quickly after using them. (The packaging said “Tactical Ammunition” so you know it’s good.)

    Of course I’m dumb for not cleaning the adjustable orifices sooner - knowing there was a problem with it but not wanting to crack it open. I’m gonna clean the bbl and gas parts real well and then shoot 500 rounds of higher quality copper jacket stuff and see if I notice the same thing happening. Otherwise just gotta make the gas block part of routine cleaning. Thanks for your help!
    Last edited by fivesidedpolygon; Yesterday at 10:30 AM. Reason: New info
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    Carbineman fivesidedpolygon's Avatar
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    Update from RA:

    “We've seen that with .300 blackout. It requires a larger gas port to cycle and we see quite a bit of brass fouling. There may be some bullets that are better than others. Haven't tested for that.

    Sincerely,
    RA Tech”
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    XCR Guru Sean K.'s Avatar
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    Quote Originally Posted by fivesidedpolygon View Post
    Thatís good info. It seems to me, and I might be wrong, but 3-4 yrs ago when I bought my suppressor there wasnít remotely as much marketing happening around flow-thru designed cans. If I had it to do over again...

    Jacket shaved off by the gas port is something Iíd never seriously considered. My gas block is type 3 (2017 upper built by RA) I was aware of copper fouling in barrels and cleaning to protect against it, but since I hadnít seen inordinate amounts of copper hiding in other places, I was pretty shocked to see that it was all getting hung up & compacted in the gas drum. Iíll check if the port is out of spec, but I donít think so and i def donít see a burr or anything in there. My pet theory is that it happened more rapidly with S&B 200 gr subsonic, because they had a brass-yellow plated jacket and the stuff I popped out of the orifices was brass colored. The problem developed quickly after using them. (The packaging said ďTactical AmmunitionĒ so you know itís good.)

    Of course Iím dumb for not cleaning the adjustable orifices sooner - knowing there was a problem with it but not wanting to crack it open. Iím gonna clean the bbl and gas parts real well and then shoot 500 rounds of higher quality copper jacket stuff and see if I notice the same thing happening. Otherwise just gotta make the gas block part of routine cleaning. Thanks for your help!

    NP. I wonder if NP3 or similar would lengthen service intervals....problem is Robar isn't doing it anymore apparently.

    I'm betting your bbl port is correct in size...but QA issues have been an RA problem in the past. It's been WAAAAY better though for years...

    Probably just the port size it needs to run the lower pressure .300 stuff.

    Good luck with it.
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

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    XCR Guru Sean K.'s Avatar
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    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-fi...ort-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.
    "Necessity is the plea for every infringement of human liberty. It is the argument of tyrants; the creed of slaves."-William Pitt the Younger

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