AR failure to coming back into battery

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    Plinker
    Rating - 100%
    15   0   0
    Mar 10, 2009
    72
    8
    I am having an issue with an AR15 coming back into battery after being fired. Here are the facts:
    - The weapon has been thoroughly cleaned.
    - After manually loading the cartridge from an empty chamber the gun fires without issue.
    - After firing the case is ejected and the next cartridge is chambered without issue, but the gun is slightly out of battery.
    - The forward assist does nothing to resolve the issue.
    - If I pull the bolt back just a bit, but not enough to eject the round in the chamber then let it slam home the gun goes into battery.
    - The non-battery issue happens 100% of the time after a shot, but 0% of the time with a manual loading.
    - I have swapped out the BCG into another AR and it works fine.
    - I put the BCG from another working AR in the "bad" one and the issue remains

    At this point, I am thinking the issue has to be the barrel. Should I simply purchase another barrel or is there something else I should do first?
     

    Chase515

    Expert
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    13   0   0
    Jan 29, 2011
    765
    28
    Oxford, In
    I had a similar problem with my m&p 15or when brand new. But it only lasted for a few mags. Is this a new gun? Or a home build? If its a home build you might have the gas block out of alingment causing a undergased short stroke.
     

    scottka

    Master
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    6   0   0
    Jun 28, 2009
    2,111
    38
    SW IN
    Yep, to echo those above, sounds like slightly undergassed or over-buffered/sprung. Need some more details. Try switching a a carbine buffer and spring into it from another AR and see if that functions.
     

    NyleRN

    Master
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    28   0   0
    Dec 14, 2013
    3,834
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    Scottsburg
    I don't believe it has anything to do with buffer or the spring. Put the upper on another lower and see it the problem persists. I bet it does. Need more info though. I'll agree with that.
     

    greed

    Plinker
    Rating - 100%
    15   0   0
    Mar 10, 2009
    72
    8
    I do not think I have mentioned, but the gun does have a low round count since purchase. Maybe 100 rounds total. I will follow up with test result when I can get back to the range.

    I do not think the gun is short stroking given that it always ejects the spent case and picks up the new round without issue. What about BCG bounce? If the gas is too high/spring is too weak and the BCG is bouncing out of battery. From what I have read/watched the spring normally pushes the BCG back into battery after a bounce, but what if the spring is too weak? If I trade lower and the problem goes away I would think the Buffer spring would be the culprit.
     
    Last edited:

    55fairlane

    Master
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    4   0   0
    Jan 15, 2016
    2,223
    113
    New Haven
    I do not think I have mentioned, but the gun does have a low round count since purchase. Maybe 100 rounds total.

    With only a hundred rounds thru the rifle....call the manufacturer and ask them to look at it/fix.....they will take care of you,that's my bet
     

    T-DOGG

    I'm Spicy, deal with it.
    Site Supporter
    Rating - 99.6%
    262   1   0
    Feb 4, 2011
    17,410
    149
    New Haven
    I do not think I have mentioned, but the gun does have a low round count since purchase. Maybe 100 rounds total. I will follow up with test result when I can get back to the range.

    I do not think the gun is short stroking given that it always ejects the spent case and picks up the new round without issue. What about BCG bounce? If the gas is too high/spring is too weak and the BCG is bouncing out of battery. From what I have read/watched the spring normally pushes the BCG back into battery after a bounce, but what if the spring is too weak? If I trade lower and the problem goes away I would think the Buffer spring would be the culprit.
    What ammo are you using? I once had a new AR and tried to run Wolf steel case right out of the gate and it wouldn't cycle correctly. I had to run brass case ammo for like 3-400 rounds to get the gun a little broke in before it would cycle the lower powered Wolf properly. Just a thought, because a new BCG will be tight when new, especially when the whole rifle is new. So if you're running under-powered ammo, that might be your problem.
     

    greed

    Plinker
    Rating - 100%
    15   0   0
    Mar 10, 2009
    72
    8
    The ammo was store bought brass cased ammo. I reload so I only use brass cased ammo. I miss an opportunity to hit the ran this weekend so it will be another week before I can get some more testing in.
     
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