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Thread: Sheared gas key bolts - Anybody run into this before?

  1. #11
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    According to the owner, he's pretty sure it's a BCM BCG. He's had it a long time and a lot of rounds. He's going to clean it and see if there is a laser etched ID on the outside.

    No word if it has made contact with the lower yet.
    Sticks

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  2. #12
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    Quote Originally Posted by GH41 View Post
    What do you see wrong with the way they are staked? Please explain why the way they are staked caused the cap screws to shear?
    I'm not saying the staking caused the break. They are barely staked. That leads me to believe that if the manufacturer couldn't be bothered to stake them properly they are more than capable of using poor quality fasteners.

  3. #13
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    Quote Originally Posted by Sticks View Post
    According to the owner, he's pretty sure it's a BCM BCG. He's had it a long time and a lot of rounds. He's going to clean it and see if there is a laser etched ID on the outside.

    No word if it has made contact with the lower yet.
    How can anyone be "pretty sure it's BCM"? The letters BCM on the side should be visible to everyone but Stevie Wonder.

  4. #14
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    Quote Originally Posted by Inkslinger View Post
    How can anyone be "pretty sure it's BCM"? The letters BCM on the side should be visible to everyone but Stevie Wonder.
    I was thinking the same thing

  5. #15
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    Quote Originally Posted by lysander View Post
    50 to 58 in-lbs.
    Thanks

  6. #16
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    Here are my initial thoughts:

    As others mentioned, the front screw looked liked it failed primarily due to over tightening.

    I'm not sure why the second screw failed. But close up pictures of the cleaned second screw (the broken areas) could be very informative.

    I could be wrong, but I don't think this is a BCM bolt carrier. The gas screws in the picture look different from the BCM screws I have seen. The BCM screws are flat top with a sharp outer edge, not slightly rounded like in the picture. The screws in the picture may be fine quality, but they are different than BCM's.

    I'm curious if the shooter had any short stroking issues, when shooting unsuppressed, before this failure.

    Joe Mamma
    Last edited by Joe Mamma; 11-29-15 at 19:55.
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  7. #17
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    That is not a BCM. Someone might have told him that, but it's not. BCM doesn't use those kinds of garbage screws.


    Quote Originally Posted by Sticks View Post
    According to the owner, he's pretty sure it's a BCM BCG. He's had it a long time and a lot of rounds. He's going to clean it and see if there is a laser etched ID on the outside.

    No word if it has made contact with the lower yet.



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  8. #18
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    Quote Originally Posted by Inkslinger View Post
    How can anyone be "pretty sure it's BCM"? The letters BCM on the side should be visible to everyone but Stevie Wonder.
    If it is old enough it might not be marked if my memory serves me. So it could be a BCM BCG that was built before they started marking them. Depending when he bought it. I would say 2012 or there abouts it damn well better be marked.

    ETA:
    I would rely on IG to know the details of the screws. If he says it ain't I'd bet money it ain't. Only thing I could think of then, is might be a BCM Bolt in an different carrier. I did see that shit back during the SH panic, among other things.
    Last edited by Kain; 11-29-15 at 20:06.
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  9. #19
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    Latest revision I have is 58 in./lbs which is like 4.66 ft./lbs.

    Quote Originally Posted by titsonritz View Post
    What is the torque spec on them?



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  10. #20
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    Highly doubtful since they don't use those screws and the stakings are nowhere close to what BCM's look like. I was working there in summer of 2012 and marked carriers and bolts were already common place.

    Quote Originally Posted by Kain View Post
    If it is old enough it might not be marked if my memory serves me. So it could be a BCM BCG that was built before they started marking them. Depending when he bought it. I would say 2012 or there abouts it damn well better be marked.



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