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Thread: Short stroking BCM bolt carrier

  1. #21
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    Labor Day sale until Tue at Noon

    https://www.surplusammo.com/products...ier-group.html

    SAA AR-15/M16 - BCG MPI -NITRIDE - .223/5.56/300AAC Complete Bolt Carrier Group $79.99

    For EMERGENCY
    SAA AR-15/M16 Bolt Assembly w/ Pins - Nitride 9310 MPI - 223/5.56/300AAC $27.99
    Last edited by RWH24; 09-06-21 at 20:57.
    POW-MIA, #22untilnone
    Let Us #NeverForget!


    If I agreed with you, we'd both be wrong.

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    but it's still on my list.

  2. #22
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    Quote Originally Posted by Tony617 View Post
    If is your only AR then I would buy a spare BCG so that way you can change over to your spare BCG and worry about it later.
    Yes, a BCG (or a couple) is one of those parts one should keep on hand.

  3. #23
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    Quote Originally Posted by MistWolf View Post
    Reverse torque check is not an acceptable inspection for final assembly (unless specifically called for by the tech data). Any fastener subjected to a reverse torque check should be loosened, the threads cleaned, inspected and re-torqued according to spec. A reverse torque can loosen the fastener without any perceptible movement leaving the fastener, not only under torqued, but loosened. Also, most torque wrenches are not certified for torque in a counter clockwise direction.
    I am sorry if I spread an unsafe method. I have no training in these things but I assume Chad Albrecht of SOTAR does. Perhaps I have misunderstood his method or where he employs it.

  4. #24
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    Quote Originally Posted by Disciple View Post
    I am sorry if I spread an unsafe method. I have no training in these things but I assume Chad Albrecht of SOTAR does. Perhaps I have misunderstood his method or where he employs it.
    It is entirely possible that Chad removes, cleans and re-torques after his "reverse torque" tests. Everything does not make it to video.

    EDIT - most torque wrenches are more accurate in the clockwise direction. Fastener torque measurements are more accurate when tightening. I am guessing in Chad's case an approximate reading is sufficient and the torque wrench adds a bit of uniformity.

    Chad is not performing final inspection after assembly in his videos, he is effectively performing a "post mortem" to identify potential issues.

    Personally, I would check for loose or broken fasteners by attempting to tighten them at the correct torque because I am too lazy to disassemble, clean, and then re-torque if they were tight in the first place. If they are loose or broken, it will be obvious either way.

    Andy
    Last edited by AndyLate; 09-08-21 at 07:02.

  5. #25
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    So what happened? Stripped threads or a broken off fastener head? Either way, my bet is they over torqued it at the factory, the fasteners were sub par, or both.

  6. #26
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    this is an informative thread. good-to-know stuff. just-in-case.

  7. #27
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    Quote Originally Posted by acaixguard View Post
    I've been looking but it doesn't seem like any quality mil-spec ones are in stock?
    BRT In Stock
    Black River Tactical
    BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
    BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
    BRT Bolt Carrier Groups M4A1, M16 CHROME
    BRT Covert Comps 5.56, 6X, 7.62

  8. #28
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    I’ve been really impressed with the AO Precision BCG that came with my URGI upper. Especially for the price they can be had at individually.
    I do wonder whether BCM will take care of you or just say it was your fault. Even if not, you’ll have a good spare bolt which is good to have.

  9. #29
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    Quote Originally Posted by AndyLate View Post
    It is entirely possible that Chad removes, cleans and re-torques after his "reverse torque" tests. Everything does not make it to video.

    MW is correct, as usual; most torque wrenches are designed to be accurate in one direction only. Fastener torque is definitely only measured when tightening. I am guessing in Chad's case an approximate reading is sufficient and the torque wrench adds a bit of uniformity.

    Chad is not performing final inspection after assembly in his videos, he is effectively performing a "post mortem" to identify potential issues.
    Chad clearly distinguishes between autopsy and physical. He has stated that he does not reuse gas keys. I do not believe he is replacing gas keys on every carrier that gets a reverse torque test as part of the physical. He uses a Wheeler's F.A.T. wrench at 30 inch-pounds. https://youtu.be/nQWGQuLyUCU?t=1035

    Quote Originally Posted by rsilvers View Post
    The military standard is that the stakes should not distort the side surfaces, and they should result in a removal torque no less than 55 and no more than 100 inch-lbs.
    If this is correct the fasteners should require at least 55 inch-pounds to break the staking. Perhaps 30 is not enough to loosen properly fastened gas key screws, but it is enough to detect sheared ones?

  10. #30
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    Quote Originally Posted by Disciple View Post
    Chad clearly distinguishes between autopsy and physical. He has stated that he does not reuse gas keys. I do not believe he is replacing gas keys on every carrier that gets a reverse torque test as part of the physical. He uses a Wheeler's F.A.T. wrench at 30 inch-pounds. https://youtu.be/nQWGQuLyUCU?t=1035



    If this is correct the fasteners should require at least 55 inch-pounds to break the staking. Perhaps 30 is not enough to loosen properly fastened gas key screws, but it is enough to detect sheared ones?
    I edited my post for accuracy. It is acceptable to measure torque when loosening a fastener. The value will be approximate, but that is certainly sufficient to verify gas key screws are correctly torqued.

    Andy

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