Page 2 of 4 FirstFirst 1234 LastLast
Results 11 to 20 of 36

Thread: how to use headspace gauges?

  1. #11
    Join Date
    Jan 2008
    Location
    AZ-Waging jihad against crappy AR's.
    Posts
    24,902
    Feedback Score
    104 (100%)
    Grant,

    I am assuming that this applies to the "civilian" gauges as they have a rim. If I remember correctly the military "Field" headspace gauge has no rim, it is tapered.

    Quote Originally Posted by C4IGrant View Post
    The reason is that can wear/damage the gauge.

    Just to be clear, you leave the extractor in, but remove the spring and insert.


    C4

  2. #12
    Join Date
    May 2006
    Location
    VA/OH
    Posts
    29,630
    Feedback Score
    33 (100%)
    Quote Originally Posted by Iraqgunz View Post
    Grant,

    I am assuming that this applies to the "civilian" gauges as they have a rim. If I remember correctly the military "Field" headspace gauge has no rim, it is tapered.

    Correct.


    C4

  3. #13
    Join Date
    Aug 2007
    Posts
    1,177
    Feedback Score
    0
    Quote Originally Posted by C4IGrant View Post
    The reason is that can wear/damage the gauge.

    Just to be clear, you leave the extractor in, but remove the spring and insert.


    C4


    gotcha, thanks!

  4. #14
    Join Date
    Dec 2006
    Location
    SouthEastern U.S.
    Posts
    1,810
    Feedback Score
    0
    Could someone educate those of us who are lacking knowledge, on this whole HS issue? I mean, is it necessary, or is it standard practice to match a bbl up with a matching bolt when building a custom AR?
    I mean, WHEN LMT, COLT, etc, are building rifles/carbines, they just grab a bolt off the assembly line, and chunk it in the next gun (bbl) that comes down the line, right?
    I am just trying to figure out when HS is an issue, and when checking HS or matching up bolts with bbls is necessary??

  5. #15
    Join Date
    Jan 2008
    Location
    AZ-Waging jihad against crappy AR's.
    Posts
    24,902
    Feedback Score
    104 (100%)
    Paul,

    When LMT, Colt etc...are slapping guns together yes you are probably right. However, all the guns are inspected to include headspace checks before they are shipped out. Since the relaible manufacturers keep their weapons within tolerances and all the parts are new there shouldn't be an issue with it not headspacing correctly.

    Quote Originally Posted by Paul Cataldo View Post
    Could someone educate those of us who are lacking knowledge, on this whole HS issue? I mean, is it necessary, or is it standard practice to match a bbl up with a matching bolt when building a custom AR?
    I mean, WHEN LMT, COLT, etc, are building rifles/carbines, they just grab a bolt off the assembly line, and chunk it in the next gun (bbl) that comes down the line, right?
    I am just trying to figure out when HS is an issue, and when checking HS or matching up bolts with bbls is necessary??

  6. #16
    Join Date
    Dec 2006
    Location
    SouthEastern U.S.
    Posts
    1,810
    Feedback Score
    0
    I gotcha. You see where I'm going with this?
    Basically, what I'm trying to determine, is IF I am buying uppers, lowers, and bcg's from various sources, then do I need to be checking HS on all my builds??
    OR, do I just need to go shooting, and call it good if the weapon performs reliably.???
    Thanks.

  7. #17
    Join Date
    Jun 2006
    Location
    Colorado Springs
    Posts
    1,857
    Feedback Score
    0
    The latter. The only time I might check is if I replace a bolt that was shot in a barrel that had a lot of wear. Bore/chamber wear has nothing to do with it though, it would the wear on the barrel extension. And even then I'd probably just slap a new bolt in and declare it GTG. If you ran into a situation where you had a new bolt that would close on a Field Reject gauge, there's no way really to adjust things other than try different bolts, with the hope you'd get one that reduced headspace back within the Go/No Go area.

  8. #18
    Join Date
    Jun 2006
    Location
    Colorado Springs
    Posts
    1,857
    Feedback Score
    0
    Quote Originally Posted by opticalc View Post
    I built an upper with a kotonics/cardinal 6.8mm SPC barrel that had the "improved" chamber.

    And why couldnt i find any 6.8mm field HS gauges?

    My 2 manson 6.8mm headspace gauges didnt come with any instructions. Now on the manson site they had a blurb about some extra things you had to be careful of when measuring headspace on improved chambers. Im not sure if that situation applies to the 6.8mm improved system.
    http://www.mansonreamers.com/Instruc...y%20Gaging.pdf
    I'm pretty sure the Kotonics Improved chamber doesn't alter HS, it only affectes the leade and freebore areas. HS guages aren't designed to extend into this area.

    What your Manson instructions refer to is using these in Ackley (or similar) chambers where the shoulder angle is changed. Again, I'm pretty sure the 6.8 improved retains the same shoulder angle and shoulder position so SAAMI HS gauges will work perfectly.

  9. #19
    Join Date
    Dec 2007
    Posts
    15
    Feedback Score
    0
    Quote Originally Posted by gotm4 View Post
    If you're using the .223 Forster gauges (the whole set), many 5.56mm NATO chambered guns will close on a NO-GO but won't (and shouldn't) on a FIELD. I usually just use a USGI FIELD to make sure there isn't excessive headspace (the dangerous kind).
    I use the Forster gauges and have declared a few rifles as "unsafe to fire" because it closed on the field gauge.

    Now my questions is, Is it still possible that those rifles will not close when using a USGI FIELD? There by making it still safe to fire?

  10. #20
    Join Date
    Jun 2006
    Location
    Colorado Springs
    Posts
    1,857
    Feedback Score
    0
    Quote Originally Posted by turnero View Post
    I use the Forster gauges and have declared a few rifles as "unsafe to fire" because it closed on the field gauge.

    Now my questions is, Is it still possible that those rifles will not close when using a USGI FIELD? There by making it still safe to fire?

    NATO is a bit more generous in its Field Reject than SAAMI. You can fail a SAAMI guage and still pass a NATO gauge.

Page 2 of 4 FirstFirst 1234 LastLast

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •