Failure to cycle
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Thread: Failure to cycle

  1. #1
    Newbie dracoman's Avatar
    Join Date
    May 2010

    Failure to cycle

    I'm having a problem with my .223 conversion barrel on XCR. Rounds will not cycle unless worked manually with the charging handle. Works as single shot. This is what I've noticed:

    Where gas block is attached to barrel there is a gap. The key of the gas block is not seated into the groove on the larger part of the barrel. It only goes into notch about 1/4 of the way. Tried loosening the allen screw but could not move closer. I did not bang hard on it.

    When sliding barrel into upper receiver the gas block is not flush with gas tube. There is about 1/8 inch gap. Barrel will not go any further.

    After screwing in barrel bolt the gap increases to approx 7/32 between gas block and receiver. The gas block will spin around inside.

    The distance from gas block to breech end of barrel is longer on .223 barrel than 7.62 barrel probably because of gap where block meets barrel.

    I am using AE 55g ammo.

    Could someone please tell me if this is causing my cycling problem. And if so how to correct it


  2. #2
    Super Moderator Underground's Avatar
    Join Date
    Dec 2008
    Murfreesboro, TN

    Re: Failure to cycle

    Yes. If the gas block is not seating correctly you aren't getting gas through to drive the action.

    Take the gas block completely off and clean it and the barrel. If it still doesn't reseat correctly look inside, you might be able to see a wear point where it's hitting.

    If it's something simple like a little piece of metal flake or something you can probably take care of it, otherwise you should contact RA to send it in (at least the barrel and gas block) for repair.

    That guy, he said I should be oblong and have my knees removed. But I don't trust him, he plays the banjo.

  3. #3
    XCR Guru BuddyChryst's Avatar
    Join Date
    Apr 2010

    Re: Failure to cycle

    Sounds like you've diagnosed the problem to me. By your post I am assuming you have a 7.62x39 kit that operates perfectly? That pretty much isolates this problem to the 5.56 barrel and gas block.

    If the gas block isn't seated properly, you're not getting gas out of the port through the block to the dial and onto the piston. Add in the gap so that any gas that is making it through is being exhausted instead of operating the piston and you've got yourself a single fire rifle.

    Underground has already given you what you need to try a self repair. If you don't have confidence in your repair abilities, I'd shoot an email off to Tech to ask for guidance on how to proceed.
    Charter member of the vast, right-wing conspiracy

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  5. #4
    Carbineman XCR-Danny's Avatar
    Join Date
    Oct 2010

    Re: Failure to cycle

    What length of barrel is it?

    Measure the port hole under the gas block using done gauge pins, if you don't have any use a drill bit that fits perfectly and let me know the size, then we can go from there.


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