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Thread: Secure your gas block, please...

  1. #21
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    Thx for reminding to check the torque on my clamp screws. I’m riding on a wing and a prayer, if shtf


    Sent from my iPhone using Tapatalk

  2. #22
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    Quote Originally Posted by Outlander Systems View Post
    Here's the deal.

    Use Bubba Assembly techniques, get Bubba results.
    Quote Originally Posted by Hmac View Post
    Exactly my point.
    From Geissele:

    Easy and Secure Installation

    All that is needed is a dimple so that the set screw enters into the dimple and does not pull up proud bumps when tightened. It also puts the set screw in shear from any axial or radial loads applied to the gas block in service. Blow out chips from drilling and install and tighten the 2nd set screw. Now remove the 1st set screw and dimple the barrel through that hole.

    Bombproof Installation

    If the weapon is going to be used in a duty or combat situation it is recommended to pin the SGB to the barrel......complete the installation using the instructions above, then follow the instructions below.......
    1. Securely mount the barrel....
    2. Align the machine spindle with the pilot hole.......this is not a super critical alignment since there is plenty of machining stock left for the pilot hole. (hence my use of my floor mounted drill press versus a mill.)
    3. Match drill through the SGB pilot hole and barrel using a 3/16” diameter drill with good quality sulfurized cutting oil. A 135 deg split point, cobalt screw machine drill works well for this step such as McMaster-Carr PN: 28765A19.
    4. Drive the supplied 3/16” spiral coil pin into the match drilled hole while backing up the SGB onto a piece of soft wood. The SGB is now secured to the rifle barrel.

    Initially I just did the 'easy and secure installation' with set screws. Since I obtained a floor mounted industrial drill press I have gone back and pinned all the gas blocks on my rifles, just to be safe. I kind of believe the If the weapon is going to be used in a duty or combat situation it is recommended to pin the SGB to the barrel.

    Folks need to have some rudimentary mechanical skills and be able to follow simple instructions to graduate from Bubba status.

  3. #23
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    People swear by there BCMs with only set screws. Mine has been 100%. I do wish it was pinned but I'm not going to loose any sleep over it. I may have it pinned if the opportunity arises. In the near future I'm looking to put together a SBR upper. One thing on the list of priorities is a pinned gas block but it's not at the very top.

  4. #24
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    Amen! I see a gas block work loose about once a month at the range I work at. Usually it's someone who took off an A2 (because they aren't high speed now apparently) and installed some budget gas block without knowing what they were doing. Or it's a home build because 'it's just like LEGOs, anyone can do it' without any knowledge about how they work.

  5. #25
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    Quote Originally Posted by 26 Inf View Post
    From Geissele:

    Snip...

    Initially I just did the 'easy and secure installation' with set screws. Since I obtained a floor mounted industrial drill press I have gone back and pinned all the gas blocks on my rifles, just to be safe. I kind of believe the If the weapon is going to be used in a duty or combat situation it is recommended to pin the SGB to the barrel.
    I'm about to pull the trigger on one of these. Was surprised at the size of the pin, though. Expected it to be like an A2 pin.

    Installed another mfg gas block with dimples for my bro, really wish they did the trick with the hole in the bottom of the block that allowed visual/pin check of alignment. Mark it, then rotate 180 degrees. Instead I confirmed with compressed air.

  6. #26
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    Quote Originally Posted by pinzgauer View Post
    I'm about to pull the trigger on one of these. Was surprised at the size of the pin, though. Expected it to be like an A2 pin.
    No kidding. I wouldn't take that much meat off of any of my barrels. I worry about the barrel harmonics and stuff.
    "You people have too much time on your hands." - scottryan

  7. #27
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    Quote Originally Posted by markm View Post
    No kidding. I wouldn't take that much meat off of any of my barrels. I worry about the barrel harmonics and stuff.
    That was most of my concern, a big divot out of a barrel creating a stress point or changing the harmonics.

    Does anyone make one that uses smaller pins? The G is 3/16" if I recall.

  8. #28
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    Quote Originally Posted by pinzgauer View Post
    Does anyone make one that uses smaller pins? The G is 3/16" if I recall.
    Noveske used to have reasonably sized pin holes on their barrel/gas block combos. But I don't know if they sell/sold the GBs individually.
    "You people have too much time on your hands." - scottryan

  9. #29
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    I'm confident that those pins on either my Noveske gas blocks or my Geissele gas blocks represent less intrusion into my barrel than any taper-pinned FSB.

  10. #30
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    Quote Originally Posted by pinzgauer View Post
    That was most of my concern, a big divot out of a barrel creating a stress point or changing the harmonics.

    Does anyone make one that uses smaller pins? The G is 3/16" if I recall.
    I kind of trust Mr. Geissele. I think he probably considered those issues.

    I took the rail off one of my 18" SS's which I did not pin. I hope it shows what I want to show. First of all the gas block journal is .750. The barrel diameter before the gas block journal is also .750. The barrel is fluted, notice the depth of the flutes. When you compare the amount of barrel visible in the hole where the pin would go, it looks to me just about the same. I'm not worried, I'll eventual pin this one.

    Of course, YMMV.

    Attachment 50877

    ETA: the gas block journal is slightly off angle, so the amount of barrel showing in the hole for the pin appears to be greater tha 1/2 the diameter of the hole, it isn't.
    Last edited by 26 Inf; 03-08-18 at 17:22.

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