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Thread: Pinned FSB vs LPGB Set Screws

  1. #1
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    Pinned FSB vs LPGB Set Screws

    Is pinning a LPGB overkill provided the barrel is properly dimpled and the proper red loctite is used?

    BCM claims they have not had any of there's come loose.

    Pinning the FSB makes sense because its exposed. The FSB is potentially a exposed 2" lever that is susceptible to being twisted or knocked out of place where as the LPGB is not.
    Big brother is watching...and listening.

  2. #2
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    I consider it a safeguard, especially if your barrel is subjected to high heat cycles. (Such as shooting suppressed.)

  3. #3
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    I don't know if it matters or helps, but I center punched the set screws on mine.

  4. #4
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    I have pinned gas blocks, pinned gas blocks with set screws in barrel dimples, and gas blocks with set screws in barrel dimples.

    None have ever come loose on me, not even the unpinned ones. Dimple your barrel, use knurled tip screws, degrease the screws, degrease the threads in the gas block, apply Red 271, torque to spec, and allow it to cure. Or you can pin it as well, it certainly won't hurt anything.
    "Don't let yourself get attached to anything you are not willing to walk out on in 30 seconds flat if you feel the heat around the corner."- Neil McCauley

  5. #5
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    Sometimes a little overkill is just right.

    Look at how wound up people get over staking carrier screws.

    These are pieces that you never want to come loose by themselves.

    Also, I'm not a fan of Loctite for most high heat applications.

    Get the gas block to 400F and it may as well not be there.
    Black River Tactical
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  6. #6
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    If it's protected by the handguard, I don't care about pinning. Dimple and set screw however is a must. We had an adjustable gas block slip on us because I got lazy and didn't dimple.
    "You people have too much time on your hands." - scottryan

  7. #7
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    How deep a dimple would you guys say is sufficient? I've used the SLR jig to double dimple all my LPGB barrels, and I probably go 40 thousandths or so and then use red Loctite, but I sometimes wonder if I shouldn't have gone 80 thou.

  8. #8
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    I have a 10.3 BA Hanson Barrel that had their lo pro gas block pinned from them.

    The pin does give me the warm and fuzzies.

    Was it a must? Probably not.

  9. #9
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    Quote Originally Posted by georgeib View Post
    How deep a dimple would you guys say is sufficient? I've used the SLR jig to double dimple all my LPGB barrels, and I probably go 40 thousandths or so and then use red Loctite, but I sometimes wonder if I shouldn't have gone 80 thou.
    Whatever is deep enough to get some bite on the set screw bevels. .040 is probably ok if your set screw is hitting the dimple good.
    "You people have too much time on your hands." - scottryan

  10. #10
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    Quote Originally Posted by markm View Post
    Whatever is deep enough to get some bite on the set screw bevels. .040 is probably ok if your set screw is hitting the dimple good.
    Cool, thanks.

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