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Unique AR15 jam. . .

Discussion in 'Rifle Country' started by edwardware, Nov 6, 2020.

  1. edwardware

    edwardware Member

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    I'm working up load data for a couple powders in a sorta-wildcat cartridge (7.62x40WT) in an AR platform. With this in mind, it could be under- or over-gassed (excessively slow or fast powder).

    As I've been working up, I've twice seen a jam that is completely unique in my experience. The mouth of a fired cartridge engages the inside of the charging handle nose, the head of the cartridge stays on (or re-engages) the bolt face, and the BCG hangs half-shut. Of course this can't be cleared from the charging handle; you need to pull the BCG back through the port.

    So, what does this FtEject suggest to you? Something about gas supply, or the bolt perhaps? The bolt appears fine, ejector and extractor are good as far as I can tell. It's occurred with recipes that usually eject and lock back, and both with and without a magazine in the well.
    IMG_20201103_182217698.jpg IMG_20201103_182251217.jpg

    Edited for Spelling, thanks @jmr40
     
    Last edited: Nov 7, 2020
  2. WestKentucky

    WestKentucky Member

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    Something likely not right with the ejector. It should be turning the case towards the window And keeping pressure on it to spit it out when the bolt retracts enough for the case mouth to clear the window. Something is turning it straight up, just gotta figure out what it is.
     
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  3. gpb

    gpb Member

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    I don't know if it's possible. I don't have an AR in from of me.

    Can an AR bolt be installed in the BCG rotated 180 degrees out of its proper position?
     
  4. WestKentucky

    WestKentucky Member

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    No. The gas key is what aligns the bolt and forces it to be properly located at time
    In install and to remain in proper location.
     
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  5. 12Bravo20

    12Bravo20 Member

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    I have seen jambs like that, not really uncommon. Definitely check that you have the correct extractor and spring and that it is set up/working correctly.
     
  6. jmr40

    jmr40 Member

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    Jam

    OIP (2).jpg

    jamb

    OIP (1).jpg

    Sorry I can't really help with the problem. Just trying to interject a bit of levity. Please don't take offense, none was intended.
     
  7. edwardware

    edwardware Member

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    And now a whole crop of various Failures to extract (and consequent double-feed). The Extractor feels ok, and yes it's pointed out the port, but I wonder if it's floating.

    The cases it fails to extract have no rim damage at all. . .

    Speeling Maaterz. . .
     
  8. Cemetery21

    Cemetery21 Member

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    Maybe, if the bolt is short stroking just the right amount, could the mouth of the case come out of the chamber but the bolt started to close before the mouth gets to the ejection port? Do similar loads lock the bolt back on an empty mag?
    Otherwise, I'd have to agree on the ejector not putting enough force on the case head.
     
  9. armedwalleye

    armedwalleye Member

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    Is it a problem unique to your loaded ammo or is it happening with factory stuff as well? At least that way, you'd be able to determine if it's a gas/ammo problem or a gun issue.
     
  10. LoonWulf
    • Contributing Member

    LoonWulf Contributing Member

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    I had a 300 blackout do that. The extractor was releasing the brass as soon as it cleared the extension. If the bolt came back fast enough it usually ejected, but if done slowly it would almost always drop the case before ejecting it. Longer .223 cases worked fine. Dunno if it's a related issue, as the WT is longer.
     
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  11. BreechFace

    BreechFace Member

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    Judging by your shell deflector it looks as if the brass that is extracting and ejecting correctly are headed in the correct direction.

    Your BCG looks dry, I run all my AR's wet, might help your scenario a bit.

    If it were me I would be looking at the extractor and ejector which it appears you have already looked at; and in particular the ejector as it looks like it isn't forcing the case towards the ejection port.
     
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  12. WestKentucky

    WestKentucky Member

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    Jammed...
     
  13. Riomouse911

    Riomouse911 Member

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    I agree, the extractor is dropping the case before it should or the ejector isn’t sending the case out the port well enough to avoid the bolt returning home. Start simple and you’ll usually solve the problem. :thumbup:

    Stay safe.
     
  14. Demi-human

    Demi-human Member

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    If it were over gassed it would leave the case in the chamber marking up or tearing off the case rim, showing the extractor weak.
    Under gassed and we’d just be talking that.

    My guess is the case rims are a bit thin for the extractor to hold on to, or the extractor groove is shallow. The next round bumps the case up, since the extractor won’t hold it to the ejector to go out.
    The bolt doesn’t pick up the next round because it gets the same one back and the case head blocks the next round.

    But, that’s just a wild guess, since you said it was Wildcat.

    What’s the “WT” stand for?

    I’d love to have an adjustable gas Nemo or some such in Thirty Aught Six. But that’s proprietary, which I’ve found more expensive than wildcat.;)
     
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  15. edwardware

    edwardware Member

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    The first test for working up was a recipe's ability to reach bolt lock without overpressure, so it's not a shortstroke.

    There is no factory ammo. . . it's entirely off the reservation!

    Maybe I haven't looked enough. I wonder if a weak extractor spring might be just enough to turn the case loose before the mouth clears the extension. . .

    I think this is where I'm headed.

    7.62x40 Wilson Tactical. It's a cool name, a SAAMI drawing, and 0.035" case length shy of the Wilson .300 HAM'R. The brass is a simple form away from 5.56, but much longer than .300BO to waste less magazine length for 110-150gr bullets.

    Thank you all, I appreciate your ideas! I think I'm going to chase an Extractor issue. . .

    762x40WT-cartridge-case.jpg
     
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  16. Demi-human

    Demi-human Member

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    Ah, I see.
    I had been looking for the wrong numbers.
    That changes the inference in the title to the jam being unique. I was thinking a proprietary AR15 fitting the maximum 30 caliber case in it possible!:)
     
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  17. edwardware

    edwardware Member

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    Apparently I can't spell at all. . . my apologies for the confusion I caused.
     
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  18. Demi-human

    Demi-human Member

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    Not at all. Who doesn’t like a good mystery!:)
     
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  19. BreechFace

    BreechFace Member

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    You learn, I learn, we all learn. It’s good to have experiences such as this to file away, especially when @edwardware has done a good job explaining what is happening.

    I’ll await what he figures out, it’ll be good to know for myself as well.
     
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  20. Charlie98

    Charlie98 Member

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    That was going to be my suggestion. I had an M16 in the Army that would do that... the fired case would, in some cases, get jammed between the upper and the gas tube, completely jamming the weapon. Armorer changed the extractor and extractor spring... and all was fine.
     
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  21. Skylerbone

    Skylerbone Member

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    If your phone has a slow motion feature you might be able to capture the incident and review.
     
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  22. entropy

    entropy Member

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    First attempt at remedy: replace extractor and spring Do not use the donut, if supplied.
    Second attempt: Replace ejector and spring.
    One of these should fix your problem.

    It is far from a unique problem. Just the first time you've experienced it.
     
  23. edwardware

    edwardware Member

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    I've seen this elsewhere, and never understood it. Provided the extractor continues to snap over the rim, why not increase spring rate?
     
  24. MistWolf

    MistWolf Member

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    If the AR doesn't have a Colt or Sprinco extractor spring, it has a weak extractor spring. The extractor may also be out of spec.
     
  25. entropy

    entropy Member

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    The donuts cause more problems than they fix. Use the right spring to begin with. (see above.) They're not needed. They're the lazy Armorer's quick fix, instead of doing the job right. I also suspect that with that gun increased spring rate won't be necessary once it is repaired.
     
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