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Thread: Bcm gas block set screws

  1. #1
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    Bcm gas block set screws

    I know they are set at .460. I have a slr jig but obviously its a .450 not a .460. Opinions on does that .01 make that big of a difference or do I just do the one dimple and call it fine

  2. #2
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    Do the 1 dimple, use the proper screws, use high temp thread locking compound, and it IS fine. Only reason you'd have to go further, like pinning the gas block for instance, is if the gas block were not going to be covered by the handguard.
    You have made us for yourself, O Lord, and our heart is restless until it rests in you. -Augustine

  3. #3
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    Shit. I just grab any larger drill bit and put a damned dimple on the barrel. So in my opinion, the difference doesn't matter. As long as the set screw can get a little bite into the circumference of the barrel, fine.

    I like to stake the set screw in IF possible. Some seat too deep, so you have to go thread lock of some kind.
    "What would a $2,000 Geissele Super Duty do that a $500 PSA door buster on Black Friday couldn't do?" - Stopsign32v

  4. #4
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    Put a single dimple opposite the gas port, that way you are not married to a specific gas block. FYI, every barrel I mentioned in your other thread came that way from the manufacturer.

    Here is Mike of SOLGW telling you the same thing...

    Gettin' down innagrass.
    Let's Go Brandon!

  5. #5
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    Barrel Dimple & Gas Block Set Screws

    A barrel dimple does two things;

    1. Ensures proper gas block alignment
    2. Ensures the gas block does not move

    To dimple your barrel the following tools will help to ensure its done properly:

    A Dimple Jig (by SLR)
    A 5/32 drill bit
    A 5/32 drill bit depth limiting stop collar
    A 5/32 transfer punch
    A 5/32 washer

    Image copy.jpeg


    Place the dimple jig on the barrel and align the pointed set screw in the gas port then snug it down. The larger drill bushing screw should be directly opposite of the gas port.

    Note:
    Only one dimple is recommended.


    Next, place the jig and barrel in a vice or drill press.


    Image.jpeg


    Now set the drill bit depth limiting collar and washer in the drill bushing and tighten the set screw. Then remove the washer.

    *The thickness of the washer will be the depth of the dimple.

    Before drilling place the 5/32 transfer punch in the drill bushing and give it a couple taps. Now its ready to drill.



    Gas Block Set Screws


    The correct Gas Block Set Screws are:
    Alloy Steel Knurl-Grip Cup-Point Set Screw, Black Oxide, 10-32 Thread, 3/16" Long
    McMaster-Carr P/N 90289A337

    The proper Torque is 10-15 inch lbs. per BCM with Loctite 272
    Last edited by prepare; 04-01-23 at 04:22.
    You won't outvote the corruption.
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  6. #6
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    Here is a video of the above /\ post.

    https://www.youtube.com/watch?v=bRwPFtV4yN0
    Last edited by the AR-15 Junkie; 04-01-23 at 04:48.

  7. #7
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    Quote Originally Posted by the AR-15 Junkie View Post
    Here is a video of the above /\ post.

    https://www.youtube.com/watch?v=bRwPFtV4yN0
    Your video provides the best way to properly do a barrel dimple and is what I based my written instructions off of.
    You won't outvote the corruption.
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  8. #8
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    Very helpful gentlemen!
    "It is better to be a Warrior in a Garden than a Gardner in a War"
    Let's use the First Amendment to protect the Second so we can avoid using the Second to protect the First.

  9. #9
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    Quote Originally Posted by the AR-15 Junkie View Post
    Here is a video of the above /\ post.

    https://www.youtube.com/watch?v=bRwPFtV4yN0
    Excellent video! Thanks for posting the link.
    Steve

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