USGI Headspace Gauges

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   Hello folks,
Years ago I acquired original in like new condition USGI headspace gauges. I have the following:
1.290, 1.295, 1.298, 1.300, 1.302 and a FIELD REJECT.

What is considered MAXIMUM allowable safety before barrel replacement or bolt replacement?

Thank you. 

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Ricci1165 Members Profile Send Private Message Find Members Posts Add to Buddy List On Point Joined: Aug 10 2018 Location: Florida Status: Offline Points: 87	Post Options Post Reply Quote Ricci1165 Report Post Thanks(0) Quote Reply Topic: USGI Headspace Gauges Posted: Jun 24 2020 at 6:37pm
	Hello folks, Years ago I acquired original in like new condition USGI headspace gauges. I have the following: 1.290, 1.295, 1.298, 1.300, 1.302 and a FIELD REJECT. What is considered MAXIMUM allowable safety before barrel replacement or bolt replacement? Thank you.

floydthecat Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Oct 13 2016 Location: Mississippi Status: Offline Points: 1998	Post Options Post Reply Quote floydthecat Report Post Thanks(0) Quote Reply Posted: Jun 24 2020 at 6:50pm
	You can find a topic "Head Space Brain Work" just a few topics down from where you posted this topic. I think it is a proven fact that carbines will continue to function beyond the length of a field, or field reject gauge. It's up the the individual shooter to determine that. I think it depends on how often you plan to shoot it and just how experienced the shooter is in terms of the mechanics of the gun and the ammo it fires. I am a proponent of using a carbine well within published tolerances that is certifiably safe, but I also think many barrels and bolts are changed just to chase a very few thousandths of an inch that may not matter.

03manV Members Profile Send Private Message Find Members Posts Add to Buddy List On Point Joined: Mar 01 2020 Location: near Charlotte Status: Offline Points: 262	Post Options Post Reply Quote 03manV Report Post Thanks(0) Quote Reply Posted: Jun 24 2020 at 11:38pm
	What is considered MAXIMUM allowable safety before barrel replacement or bolt replacement? Depends on who you ask- GI reject gage is 1.302 for "Field" use; in a rear echelon armory over 1.295 or 1.298(depending on to which time frame you refer) would be rejected and re-barreled for carbines that were to be re-issued. If you consider a maximum head space, minimum bolt and minimum cartridge, you may have up to 20-22 thousandths headspace; with tolerances the opposite way you might have only 5 thousandths! I believe what Floyd said is true. IMO, any given carbine would have to be evaluated individually using proper gages and a field test bolt. Specific results would determine if "OK" or some action were needed- perhaps a bolt change would be sufficient or a barrel change if really bad.
	Don

floydthecat Members Profile Send Private Message Find Members Posts Add to Buddy List Hard Corps Joined: Oct 13 2016 Location: Mississippi Status: Offline Points: 1998	Post Options Post Reply Quote floydthecat Report Post Thanks(0) Quote Reply Posted: Jun 25 2020 at 7:35am
	I don’t think any of us here would suggest firing a carbine until it blows-up in your face. If one is unsure what to look for and is uncomfortable about shooting one, then by all means correct it by-the-book and be safe. There are danger signs one can look for to determine just what’s going on in a carbine action. Light primer strikes, failures to fire, primers backing out, reading fired brass and observing the lock-up are a few important ones. I have one carbine that measures 1.309. I know it’s loose, but I also know that it exhibits no signs of failing. I don’t shoot it very often, but I am not afraid to shoot it when I do. I ran across another that measured 1.3115. Would fire 3 out of 5 times due to light primer strikes and occasionally backed-out a primer. Always locked up and never stressed any brass, but obviously it required attention. Carbine actions are designed loose. Like already mentioned, it gives you 20-22 thousandths of head-space going out the gate. If you manage this tolerance and stay within it watching your brass length, probobly not going to have any issues and the gun will tell you early enough when you do.