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Thread: BCG

  1. #1
    Join Date
    Dec 2011
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    Default BCG

    Swapping one (psa full auto) to another upper where an (economy mil spec) was removed. Fit is stiff and bcg “sticks when fully seated... It appears the bolt lugs is where the issue is. Is this common and if so what’s the solution? Added a little oil which seemed to help a little but still have the issue.
    “Get out among the mountains and trees, friend, as soon as you can. They will do more for you than either man or woman could.” Theodore Roosevelt to John Muir after his wife's passing in 1905.

  2. #2
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    I’ve had 2 PSA phosphate BCGs that had issues similar. Swapped them out for PSA Nickel boron and no issues after that.

  3. #3
    Join Date
    Mar 2002
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    Measure the length of each lug around the bolt. I had a PSA ‘full-auto’ BCG that had a lug or two that were over the max spec of .278”. It was causing all sorts of jamming problems.

    The same type of problem could be with the barrel extension whereby one or two of the lug slots may be under spec.

    I pulled the spec up again... .278" +- .002 or .276-.280.

    I have seen them from the .278 max down to an LMT at .272".

    To figure the important headspace measurement, measure the lugs then subtract the depth of the recess. The difference should be .150-.153".
    Last edited by WoodieSC; 09-21-2018 at 09:45 AM.
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  4. #4
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    Thx biggie and Chuck.. got it to what I think may be an operable point. Gonna run a few rounds through it and see where we’re at. It worked fine in the other upper hoping it’s just some carbon I didn’t quite get clean.
    “Get out among the mountains and trees, friend, as soon as you can. They will do more for you than either man or woman could.” Theodore Roosevelt to John Muir after his wife's passing in 1905.

  5. #5
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    Out of curiosity is the upper cerakoted?

  6. #6
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    Dec 2011
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    Negative.. 25rds with no issues. I’ll bathe it good and put a couple hundred through it another day when I have more time. Apologies for what appears to be a premature post for a non-issue.
    “Get out among the mountains and trees, friend, as soon as you can. They will do more for you than either man or woman could.” Theodore Roosevelt to John Muir after his wife's passing in 1905.

  7. #7
    Join Date
    Jun 2013
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    Johnston, SC
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    I have built over 50 uppers in the last 12 months and some clients use psa bcg's and can honestly say not a single issue with them, other psa parts I can't say that for. The premium psa bcg's are Toolcraft parts they assemble and imo Toolcraft make some of the best if not the best bcgs. What brand barrel do you have? I have had some barrel extensions have issues with the extension and causing some sticking or mauling of the metal on the bolt. I would look for sharp edges there first and if possible try a different bcg in it as well. If the lugs on the bolt are mauled a little you can carefully file it to fit as well, something we have to do on 308 ar's a good bit actually.

  8. #8
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    Jun 2013
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    Johnston, SC
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    Also, run it soaking wet at first. Best solution to most AR issues is lots of oil

  9. #9
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    Dec 2011
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    Did exactly that with the oil... hopefully that’s got it. Again thx for all the info
    “Get out among the mountains and trees, friend, as soon as you can. They will do more for you than either man or woman could.” Theodore Roosevelt to John Muir after his wife's passing in 1905.

  10. #10
    Join Date
    Dec 2010
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    28,019

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    Not normal, I have done a bunch of them.
    Slap the oil to it and run it some.

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