Bedding a gas block

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  • Jasunderland
    Unwashed
    • Jan 2018
    • 11

    Bedding a gas block

  • outbreaker
    Warrior
    • Feb 2018
    • 145

    #2
    I bed every gas block (and barrel extension) with Loctite 620. I go around and up the sides about .75 of the way leaving the 1/4 of the dia around the gas port. Place it. Secure the block. Then clean it and let it set.

    I have heated my gas blocks and barrels to remove them from this......and they are too hot to touch. I NEVER get my barrels that hot shooting them. When I remove the barrel nut it is a PITA to get the barrel out of the upper. But I know that it improves accuracy bigtime.

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    • LRRPF52
      Super Moderator
      • Sep 2014
      • 8569

      #3
      TDP calls for a tight gas seal of the block over the journal on Mil-Spec guns.

      This is why so many home builds don't run reliably, and I've seen that for years in high volume courses. Other instructors have seen and reported the same. #1 problem with most home builds in incorrectly installed gas block.

      The problem for parts suppliers is that they need to sell gas blocks that the amateur can install without a lot of specialized equipment like jigs, presses, drill presses, etc.

      So most gas blocks are a slip fit, not a press or interference fit.

      Slip fit blocks allow leakage, which doesn't pressure up the Stoner internal expansion system in the carrier, and you get short-stroking of the action with FTFeeds.

      Bedding the block is one way to deal with it that a home builder can do, but a press-fit block or sealed design block/journal interface is superior.

      The gas tube interface with the gas block is another primary culprit in gas leakage and inconsistent performance.

      KAC addressed this with their MOD 2 gas system.

      LaRue has a special ferrule that attaches and seals the gas tube into the block, along with a pinned gas block.

      The best gas block-to-journal fitting is controlled under one roof by a competent manufacturer with a good production management and Total Quality Management program, with many years of experience making AR15s. With specific test protocols in place to focus on the fit and alignment of the gas block, gas port, and journal, a very reliable AR15 can be manufactured.

      The amateur/new builder will insist it's a simple operation of slapping the parts together. The mechanical engineer or machinist with AR15 experience will disagree.
      NRA Basic, Pistol, Rifle, Shotgun, RSO

      CCW, CQM, DM, Long Range Rifle Instructor

      6.5 Grendel Reloading Handbooks & chamber brushes can be found here:

      www.AR15buildbox.com

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