G&R Tactical
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Thread: Can't get bolt to lock back after final round BCM 9" 300 blk with MVB PDW stock

  1. #11
    Join Date
    Nov 2010
    Location
    MI
    Posts
    2,227
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    Quote Originally Posted by cpoth View Post
    Thank you. I only have 300 or so rounds through it. Maybe it will work it’s way through. Of note this has happened with multiple different magazines. So I don’t think it’s a mag issue. I think the cycling is actually too fast and doesn’t allow the follower enough time to stop the bolt. MVB makes many different buffers so I have an email out to them for advice too.
    Cyclic too fast is a definite possibility, especially with a suppressor.

    But first, with the non standard MVB buffer, the static stroke should be checked to ensure the bolt goes ~.25" past the bolt catch.

    Then start looking at dynamic issues such as mass, gas and spring force.
    Black River Tactical
    BRT OPTIMUM Barrels - 16" BRT EXT Gas System
    BRT Covert Comps 7.62 + 5.56 + 9mm
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports
    BRT MicroPin Gas Blocks .750" & .625"
    BRT MarkBlue Gas Tubes - BRT EXT and PDW Lengths

  2. #12
    Join Date
    Apr 2012
    Location
    PA
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    151
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    15 (100%)
    Just to update and thank all who have shared info. I have discussed case w MVB they agree and suggest H2 buffer. Will report back when I get a chance to try it out.

    Thanks again.

  3. #13
    Join Date
    Apr 2012
    Location
    PA
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    151
    Feedback Score
    15 (100%)
    I want to follow up and thank everyone. My bolt locks back on last round with all three listed rounds from the original post. I used the MVB industries bolt, added the heavy weight from a spare H2 buffer (which is what is in their proprietary H2 buffer) and it runs without issue through approximately 200 round test.

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