View Poll Results: Round count and bolt failures with mid-length gas systems.

Voters
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  • Bolt failed under 2,500 rounds

    4 5.00%
  • Bolt failed under 5,000 rounds

    2 2.50%
  • Over 5,000 rounds with no bolt failure

    49 61.25%
  • Bolt failed under 10,000 rounds

    2 2.50%
  • Over 10,000 rounds with no bolt failure

    12 15.00%
  • Bolt failed under 15,000 rounds

    0 0%
  • Over 15,000 rounds with no bolt failure

    1 1.25%
  • Bolt failed under 20,000 rounds

    0 0%
  • Over 20,000 rounds with no bolt failure

    6 7.50%
  • Bolt failed: unknown number of rounds

    4 5.00%
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Thread: Who has broken a bolt with a mid-length gas system?

  1. #1
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    Who has broken a bolt with a mid-length gas system?

    When middies first hit the market it was widely proclaimed that the system should exhibit lower wear and reduced parts breakage.

    I have personally experienced or witnessed numerous bolt failures (broken lugs, break at the cam-pin hole) with carbine gas guns.

    However, while there are plenty of folks running around with middies, there hasn't really been any data collection. Carbine gas has had military scrutiny and data collection for about 20 years now.

    So, there's the poll:
    How much have you shot through single samples, and when did it break?
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

  2. #2
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    I've not broken one myself but replaced 3 broken midlength bbl bolts for a local LE agency.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  3. #3
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    Who as broken a bolt with a mid-length gas system?

    Quote Originally Posted by Robb Jensen View Post
    I've not broken one myself but replaced 3 broken midlength bbl bolts for a local LE agency.
    Any idea of the round count or firing schedule of those bolts?
    This isn't an illegal gun, it's an "undocumented protection device". Don't be so insensitive.

  4. #4
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    Poll up
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

  5. #5
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    Quote Originally Posted by Failure2Stop View Post
    Poll up
    Did you have to add the last option?

    I still think Filthy 14 is telling. Broken bolt lugs at 16,400.

    Though, since firing schedules of most people is less, I think the bolts will last...forever.

  6. #6
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    Quote Originally Posted by Robb Jensen View Post
    I've not broken one myself but replaced 3 broken midlength bbl bolts for a local LE agency.
    manufacturer of these bolts?..
    never push a wrench...

  7. #7
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    Quote Originally Posted by ra2bach View Post
    manufacturer of these bolts?..
    Armalite whole guns made during the Federal AWB, clamp on FSB. All bolts failed in less than 5K rounds.
    Chief Armorer for Elite Shooting Sports in Manassas VA
    Chief Armorer for Corp Arms (FFL 07-08/SOT 02)

  8. #8
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    Ooh can I click the button?

    I personally haven't broken a bolt, but my father's Colt HBAR cracked a lug at roughly the 11,000 round mark, which isnt a middy but oh well.

    Jack, I've heard that KAC has never had a broken Bolt, is this true?
    Last edited by VIP3R 237; 06-06-13 at 14:06.
    I paint spaceship parts.

    Quote Originally Posted by Failure2Stop View Post
    Stippled Glocks are like used underwear; previous owner makes all the difference in value.

  9. #9
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    I have not emptied enough brasss to break a bolt yet.

    It is my belief that:
    both gas drive (gas port size / suppressor) and gas system length / barrel length play major roles in determining the level of stresses involved during unlocking and extraction that can lead to parts failures.

    Buffer weights, bullet weights and pressure curves matter too.

    The whole thing is a system of inter-related factors.

    It's more complicated than just middie vs CAR.
    Last edited by Clint; 06-06-13 at 12:31.
    Black River Tactical
    BRT OPTIMUM HFCL Barrels - Hammer Forged Chrome Lined 11.5", 12.5", 14.5"
    BRT OPTIMUM Barrels - 16" MPR, 14.5" MPC, 12.5" MRC, 11.5" CQB, 9" PDW
    BRT EZTUNE Preset Gas Tubes - CAR and MID
    BRT Covert Comps 7.62, 5.56, 6X, 9mm
    BRT MarkBlue Gas Tubes - BRT EXT, EXC and PDW Lengths
    BRT MicroPin Gas Blocks - .750" & .625"
    BRT MicroTUNE Adjustable Gas Blocks
    BRT CustomTUNE Gas Ports

  10. #10
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    Re: Who as broken a bolt with a mid-length gas system?

    Quote Originally Posted by Clint View Post
    It is my belief that:
    both gas drive (gas port size / suppressor) and gas system length / barrel length play major roles in determining the level of stresses involved during unlocking and extraction that can lead to parts failures.
    Yup, that's the assumption, looking for the data to support.



    Typos brought to you via Tapatalk and autocorrect.
    Jack Leuba
    Director, Military and Government Sales
    Knight's Armament Company
    jleuba@knightarmco.com

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