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Thread: Pinned FSB vs LPGB Set Screws

  1. #11
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    I stopped counting but 7000, 8000, or 9000 rounds later and my set screw gas-block has not moved or come loose at all. The barrel is dimpled. Red Lock-tite was used and I staked the screws in place. One and done.

  2. #12
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    Quote Originally Posted by TomPenguin5145 View Post
    I stopped counting but 7000, 8000, or 9000 rounds later and my set screw gas-block has not moved or come loose at all. The barrel is dimpled. Red Lock-tite was used and I staked the screws in place. One and done.
    I don't believe the OP is concerned about round count, but instead of gas block being twisted or knocked out of place, like a lever. His words, not mine.
    Last edited by the AR-15 Junkie; 11-22-19 at 23:51.

  3. #13
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    Quote Originally Posted by Clint View Post
    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.
    Rocksett is the preferred chemical for gas block screw threads.

  4. #14
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    Run KAC LPGB's on 6 rifles with nary a prob.

    Form 1'ing two rifles next week and both have KAC LPGB's.

    The two screws per block work well.

  5. #15
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    I recommend pinning the gas block. I have seen screws come loose after a barrel has been dimpled and after red locktite was applied.

  6. #16
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    To answer this question for myself I once installed a set screw gas block into a properly dimpled but inexpensive barrel. I found that no amount of abuse up to and including beating the gas block with a hammer would cause it to budge at all.

    If a staked screw is good enough for your bolt carrier group then it's more than good enough for your gas block. It takes a lot of force to extract the screw from a lightly staked gas block and I actually broke the hex trying to back the screw out of a heavily staked gas block. Either way that screw is never going to wiggle out of there on its own.

    I did have a lock tited screw come loose on an upper before I started staking the screws. The gas block was still fused to the barrel by carbon and I had to beat it with a rubber mallet to get it loose. The only way it would have rotated is if the rail had been crushed.

    The bottom line is that if you have a properly dimpled barrel with a properly installed and staked screw I am supremely confident that it is not going anywhere under any circumstances short of those that would otherwise render the firearm inoperable.

  7. #17
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    Quote Originally Posted by the AR-15 Junkie View Post
    I don't believe the OP is concerned about round count, but instead of gas block being twisted or knocked out of place, like a lever. His words, not mine.
    Ok. After 6000 to 8000 rounds and 3 years of use I have not knocked the gas block out of alignment. Riding loose in a trunk of a car, riding in a rack with a helmet slung off it, training with barricades, busting my butt falling in to holes in the frozen woods of Alaska at night and its never moved or twisted.

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