Results 1 to 14 of 14
  1. #1
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,793
    Downloads
    1
    Uploads
    0

    Checking headspace

    So...about there with my project..Going back and forth on this, as Iíve built many 556 with no guages other then a field.Then got a gauge set and checked builds ever since..never had one out of spec..

    But the 308 platform, since there is no mil spec per say..

    How critical or worried should I be?

    Get the gauges and check it or roll on?

    I donít see myself building another anytime soon

  2. #2
    Join Date
    Sep 2018
    Posts
    3
    Downloads
    0
    Uploads
    0
    Get the go and no-go gauges. Better safe than sorry.


    Sent from my iPad using Tapatalk

  3. #3
    Join Date
    Aug 2014
    Location
    Mn.
    Posts
    1,260
    Downloads
    0
    Uploads
    0
    I would check it. Maybe someone here can loan you them...
    The best way to survive a violent encounter is to be the one inflicting the most violence.

  4. #4
    Join Date
    Nov 2013
    Location
    Seattle, WA
    Posts
    1,359
    Downloads
    0
    Uploads
    0
    If you know you have matched a DPMS bolt to a DMPS barrel (or Armalite bolt to Armalite barrel), you're probably fine if the components are coming from reputable manufacturers. If in doubt, I'd expect a local gunsmith could test the headspace for you for a few bucks or you could find some gauges to borrow.

  5. #5
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,793
    Downloads
    1
    Uploads
    0
    Quote Originally Posted by GeorgeandSugar View Post
    Get the go and no-go gauges. Better safe than sorry.

    Sent from my iPad using Tapatalk
    Your not new, but first post...welcome kinda sorta......Your comment got my brain thinking....

    No this wonít turn into the 2 page thread/replies like someone here.......

    But say youíve got a 308/762 match/hybrid chamber of the sorts.. One would use the 762 guages?

    Or am I overthink this? In the past when I didnít have guages Iíd set up a few dummy rounds at the datum line number and use them ( well to the closes I could)recheck after to make sure they didnít push in etc... But donít have the means to do that with 308 stuff.. I could throw in a 308 and 762 rd and pull firing pin.....and see if it closes etc....

    And no ive never had a single ar not be in spec or have problems of the sort...

  6. #6
    Join Date
    Sep 2018
    Posts
    3
    Downloads
    0
    Uploads
    0
    Quote Originally Posted by mustangfreek View Post
    Your not new, but first post...welcome kinda sorta......Your comment got my brain thinking....

    No this wonít turn into the 2 page thread/replies like someone here.......

    But say youíve got a 308/762 match/hybrid chamber of the sorts.. One would use the 762 guages?

    Or am I overthink this? In the past when I didnít have guages Iíd set up a few dummy rounds at the datum line number and use them ( well to the closes I could)recheck after to make sure they didnít push in etc... But donít have the means to do that with 308 stuff.. I could throw in a 308 and 762 rd and pull firing pin.....and see if it closes etc....

    And no ive never had a single ar not be in spec or have problems of the sort...
    This should help. Check 308 forum.

    Pacific Tool and Gauge offers three lengths of headspace gauges per rifle caliber. In order from the shortest to longest, they are: GO, NO-GO, and FIELD:

    GO: Corresponds to the minimum chamber dimensions. If a rifle closes on a GO gauge, the chamber will accept ammunition that is made to SAAMIís maximum specifications. The GO gauge is essential for checking a newly-reamed chamber in order to ensure a tight, accurate and safe chamber that will accept SAAMI maximum ammo. Although the GO gauge is necessary for a gunsmith or armorer, it usually has fewer applications for the collector or surplus firearms purchaser.
    NO-GO: Corresponds to the maximum headspace Forster recommends for gunsmiths chambering new, bolt action rifles. This is NOT a SAAMI-maximum measurement. If a rifle closes on a NO-GO gauge, it may still be within SAAMI specifications or it may have excessive headspace. To determine if there is excessive headspace, the chamber should then be checked with a FIELD gauge. The NO-GO gauge is a valuable tool for checking a newly-reamed chamber in order to ensure a tight and accurate chamber.
    FIELD: Corresponds to the longest safe headspace. If a rifle closes on a FIELD gauge, its chamber is dangerously close to, or longer than, SAAMIís specified maximum chamber size. If chamber headspace is excessive, the gun should be taken out of service until it has been inspected and repaired by a competent gunsmith. FIELD gauges are slightly shorter than the SAAMI maximum in order to give a small safety margin.

    http://pacifictoolandgauge.com/saami...-go-field.html

    https://forum.308ar.com/topic/1865-g...uage-question/


    Sent from my iPad using Tapatalk

  7. #7
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,793
    Downloads
    1
    Uploads
    0
    Thanks for the link..Some good info over there

  8. #8
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,793
    Downloads
    1
    Uploads
    0
    Well it was gonna bug me if I didn’t check it. Luck has it local guy I know from another forum (and member here) is helping me out with a set of guages.

  9. #9
    Join Date
    Sep 2018
    Posts
    3
    Downloads
    0
    Uploads
    0
    Quote Originally Posted by mustangfreek View Post
    Well it was gonna bug me if I didnít check it. Luck has it local guy I know from another forum (and member here) is helping me out with a set of guages.



    Sent from my iPad using Tapatalk

  10. #10
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,793
    Downloads
    1
    Uploads
    0
    Ok.. busy day and got the barrel and guages today, but snuck out to play once everyone was asleep.Follow along to what looks like a slightly tight chamber..

    Ok , using a slightly used Rainier arms barrel with hybrid chamber and brownells/supposedly toolcraft nitride bcg/bolt. The guages are Clymer .308 win , go guage is 1.630 and No Go is 1.634

    Barrel was cleaned and cleaned again. As was the Bolt , which was stripped down. Upper is not assembled, checking before hand.

    Insert the Go guage and the bolt will not rotate, starts to but not all the way , put bolt into bcg and try again.It begins to turn but not all the way. Does not close on the No Go...So I was curious so if grabbed some ammo.

    Inserted a fresh .308 -federal 165gr and the bolt turns on it. Like butter. Throw in a newish LC 762 150gr rd and it turns but with some resistance.. Not a lot but itís not butter..

    Colored up each of them with a sharpie , in and out a bunch times, rotating bolt. They both are hardly even scuffed. My pic sux as it looks screwy thru the pic. but itís clean..but no gouges or scrapes like it was on the lands...

    So appears to be on the tight side..whatcha think?
    Attached Images Attached Images   

  11. #11
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,793
    Downloads
    1
    Uploads
    0
    Little update if your following..

    Hit up the local known gunsmith, and he says he sees a lot of this with the Clymer guages and “match” chambers

    He played with some guages for a few. Then a few swipes with a final reamer and now it chambers on the Go guage I have, tightly. But his match guage like butter.

    Chambers a 308 like butter but 762 will chamber, just some resistance.

    And rainier barrels are not guaranteed to work “reliably” on 762 ammo, per a reply from someone at rainier.



    This is still all apart,will assemble and test fire soon

  12. #12
    Join Date
    Mar 2013
    Location
    The Unfree State (MD)
    Posts
    2,577
    Downloads
    3
    Uploads
    0
    I would have tried other bolts before I touched that chamber.

  13. #13
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,793
    Downloads
    1
    Uploads
    0
    Quote Originally Posted by SINNER View Post
    I would have tried other bolts before I touched that chamber.
    Well I don’t have any extras, or have anyone local I could of asked. New bolts about more then this complete bcg was.

    I don’t know.. not my first Rainier tight/short chamber though..years ago had a 223 wlyde/match that wouldn’t co operate till 2 barrel exchanges..

  14. #14
    Join Date
    Sep 2013
    Location
    WA
    Posts
    3,793
    Downloads
    1
    Uploads
    0
    Ok.. well I had emailed brownells days before I decided to screw with taking it up to the smith. Well I have not been getting any replies from others I had sent...long to the short they sent me another bcg to try.

    Well stripped it down, then the bolt and tried the guages again. Not happening , wonít even turn with really hard pressure..So this one is just a hair tighter then the other bolt.

    So a just tight as fook chamber. So will throw together soon , but need to get a gas tube still. INT. length, to actually try it

Posting Permissions

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