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Thread: Bolt lock back issue

  1. #1
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    Bolt lock back issue

    I have a BCM mid-length mod 2 complete gun with BCM BCG and I am having a problem with my bolt locking back on the last round. The ammo I am using is PMC bronze 223. I know it is a low pressure round but what is bothering me is when I changed out my BCM BCG with my DD BCG the bolt locks back every time. I am using magpul pmags. Can anyone give me some advise on what could be the problem or what to do. Any info is appreciated.

  2. #2
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    Try one step lighter buffer as a start. PMC Bronze and middies can be tricky together.

  3. #3
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    Worth asking if you have a BAD lever installed, they can make things temperamental.
    Dan

  4. #4
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    Is it a new rifle? have you tried any NATO rounds. what buffer is in rifle

    I am betting less then 500 rounds thru rifle, under powered ammo and a heavy buffer.

    but I have been wrong before

    I thought I was wrong once but I was mistaken
    Last edited by Colt guy; 04-15-13 at 20:46.

  5. #5
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    Must be related to the BCG.

    Try swapping bolts and narrow it down to bolt or carrier.

    Check the gas key and bolt gas rings
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
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  6. #6
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    Yes it is a brand new rifle and I only have about 60 rounds through it so far. It has the stock H buffer that came withit. Also I did try 556 rounds tthrough it and it does fine. What was weird is I shot some pmc through it a few times now and the bolt locked back a couple of times then I would shoot it again and then it wouldn't lock back at all. Every time I put my DD BCG in my BCM the bolt would lock back every single time. To me it makes no sense but I am still learning.

  7. #7
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    Quote Originally Posted by jdm View Post
    ... To me it makes no sense but I am still learning.
    Are both bolt carriers the same, f/a, s/a... If the BCM bolt carrier is f/a and the DD is s/a then the difference in bolt carrier weight could do it. Are you using the same mag each time? Tolerances in the bolt carrier and gas rings can make a difference. Because it locks back intermittently with the BCM BCG tells me you are right on the cusp of functioning properly. The slightest difference in a tolerance can make the difference.

  8. #8
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    Yes both BCG are F/A and it happens using pmags lancer mags and usgi mags as well. Most of the time I use pmags so I tried some others as well and it did it with them also. I do not have a bad lever installed on my bcm.
    Last edited by jdm; 04-16-13 at 01:46.

  9. #9
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    How many rounds has the dd bcg seen?
    " If i cannot be a good example Lord, let me be a terrible warning"

  10. #10
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    The DD BCG has only 30 rounds max. The DD I have is v5 which is also a mid length rifle. The one thing that I can tell about my DD BCG is the bolt is a little easier to push into the bcg because the bolt on my bcm is a pain in the ass some times to push in the bcm bcg.
    Last edited by jdm; 04-16-13 at 02:23.

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