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Thread: Headspacing issues

  1. #11
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    Olddog,

    If I'm reading you right, NONE of the gauges would close.

    The field is even larger than the no go, so that won't solve anything.

    It sounds like your headspace is at or below minimum, especially since the live rounds chambered without issue.

    Since you have access to the DPMS BCG, try swapping them and checking headspace on both.

    Your chamber/bolt combo may be right at minimum and may pass with a different bolt.
    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
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    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"
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  2. #12
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    I would not shoot a rifle that won't close on the GO gauge. You don't know how much shorter the HS is.

    Clean the chamber and gauge very carefully and try again. Try to get a couple of different bolts to check with next.

  3. #13
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    Glock Certified Armorer
    Armed Protective Services II

  4. #14
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    Good info there.

    Quote Originally Posted by Blankwaffe View Post
    OP, is your GO gage marked with its actual headspace dimension, IE: 1.4636 or something close to that?
    B.A.S. Mechanical Engineering Technology

  5. #15
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    In my limited experience,if the rifle easily chambers and extracts/ejects rounds normally without issues or damage to the cartridge(i.e. change to COL,leade marking bullet ogive,deformed cartridge shoulder etc.).I call it good to go.

    As Bill Alexander detailed expertly in that post I linked,the barrel/bolt combo's Ive had that wouldn't close on a GO,but will chamber rounds without issue, all settle in after a few hundred rounds to near match quality in regards to headspace.I actually prefer a combo a bit on the tight side right out of the box.

    That said,if there is doubt always investigate for other issues such as short leade/throat,but if none are found, I'd bet the parts wear into near perfect headspace in regards to the GO gauge.

    If it bothers you,and the parts are in spec and no defects,swap bolts around until you get a good match on the GO.
    Glock Certified Armorer
    Armed Protective Services II

  6. #16
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    A couple notes on the headspace gauges:

    The GO is the shortest. It represents the min length for a new chamber.

    The NO GO is 3-6 thou longer than the GO and represents the max length for a new chamber.

    A new barrel/bolt that doesn't pass the GO/NO GO check should not leave the factory.

    The FIELD is the longest. It is 3 thou longer than the NO GO and represents the maximum limit of serviceability.

    A used barrel/bolt that doesn't pass the FIELD check should be removed from service and replaced.

    As a barrel/bolt is used, mating surfaces wear in and headspace slowly grows.

    The 3 thou difference between the maximum factory check and the field check allows a useful service life for the weapon.

    Obviously, an assembly at the upper limit of factory headspace will reach the field limit more quickly than one that started at the lower limit.

    It is generally desirable for a new assembly to be just above the min spec.
    Last edited by Clint; 09-15-13 at 11:41.
    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

  7. #17
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    thanks for all the replies Gents. I suppose to just be on the safe side I will send it back for a replacement. It's kind of funny because first the Shield had to go back recently, then another part from Mesa Tactical and now this. Talk about a strange last two months

  8. #18
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    It is also possible to have headspace gauges that are oversized.


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

  9. #19
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    Yes, and sometimes this is purposeful.

    A certain well known high end barrel manufacturer, uses graduated sets of headspace gauges.

    So instead of a 2 piece set that checks min and max, they use something like a 6 piece set that checks the exact headspace in .0005" increments.

    They have a specific target for headspace length and can swap and measure until they hit it.

    Quote Originally Posted by Failure2Stop View Post
    It is also possible to have headspace gauges that are oversized.


    Typos brought to you via Tapatalk and autocorrect.
    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. #20
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    Jack and Clint summed it up pretty well... I have had barrels that would not close on a GO gauge from company X, but would close on a gauge from company Z

    The pisser is when you check a barrel with an X gauge and it does not close... so you send it back to the manufacturer, who checks it with a Z gauge and says it is fine... 0.0005 is next to nothing, but that much metal will keep you from twisting a bolt closed with you fingers.

    Lots of times, when the bolt will not close, you can put an allen wrench or something in the cam pin hole and close it with that little extra mechanical advantage... often it is a little chrome build up in the throat area... or a burr or something... I polish the chambers on every rifle I build and have had many that would not close on the X gauge, then I polish the chamber and all is well... it is impossible to tell you if it is okay or not without having it in hand though.

    Bottom line is you have to be comfortable with it... do what it takes to make that so.
    Please let me know if I have offended you...
    I would like to move on to my next task.


    I provide legal consultation and training - specializing in the Law of Gravity.

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