Change bolt - change headspace?

[Scott2K]

I'm trying to put a 2,599,xxx Garand back to stock parts. I need a -12 S-A1 heat lot bolt.

When (if) I replace the bolt, will it affect the headspacing or are they uniform enough that it should be OK?

I'll check the headspace anyway for safety, but if I will probably need to re-headspace the rifle, I probably won't get the bolt.

-Scott

Information

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[Bill Hollinger]

Scott, I have changed a few bolts and for the most part they space fine. There are a few that will not though. Winchesters seem to be rather picky.

[muskydope]

For about $25 you can get an '06 field guage, strip the rifle and the bolt. Drop in the the guage... if the bolt closes... well your sunk... the lug should show an 1/8" or better till close. If it looks like that your within specs. Reassemble the rifle and bolt, check all is tight (bolt's fit in receiver) and give her a go.

[muskydope]

I got my "info" from a site called " M1 GARAND ARMORY" I found from this site. The site gives you all the info you need to not only check your rifle, but install a new barrel, ream, headspace, check headspace, etc. I used it for my H&R which was"correct" with exception of ; bolt ( '43 Winchester, and Gas Lock). Well, I found both parts ( Numerich(lock), Dupage Trading(bolt) and wanted to be sure the rifle was safe to fire before I headed out to the range. So I got the "guage", the new bolt ( HRA UW- heat lot) measured up the same as the Winchester bolt, and the rifle shoots fine.

[sigman2]

I have swapped bolts on several rifles. All have passed with the "No-Go" gauge. I may just be lucky though.

[Devil Dog]

I bought 10 CMP ceremonial barreled actions and bought 10 DuPage parts kits.
I expected some headspace issues and expected to do some "bolt swapping", but ALL passed easily with out bolt swapping. None would close on a "NO GO" gauge. I never needed to try the "field reject" gauge. These were all USGI S.A. bolts from various years.
There is a very good chance you will not have a problem.

[latigo 1]

For about $25 you can get an '06 field guage, strip the rifle and the bolt. Drop in the the guage... if the bolt closes... well your sunk... the lug should show an 1/8" or better till close. If it looks like that your within specs. Reassemble the rifle and bolt, check all is tight (bolt's fit in receiver) and give her a go.

You don't need an 1/8" clearance to pass the Field test. As long as it does not close it passes. If you have any doubts check with the manufacturer of the guages you are using. You should also check with a go guage to be sure the new bolt is not too tight.

[LavaTech]

There's plenty of variation even within the same drawing#/heat lot. I just checked a swap of -12/S06<> bolts to go from 'purty challenged to very 'purty, and the challenged bolt would pass go - the very 'purty WOULD NOT CLOSE by FAR. The 'purty challenged bolt also didn't appear exceedingly worn either, lugs or anywhere else - but the finish sure lacks beauteousness.

[Scott2K]

I checked current headspace by putting layers of Scotch tape over the primer and trimming it flush with the case head. 1 layer of tape would close on my known good bolt, 2 was snug, 3 was tight enough I had to push it closed with my thumb fairly hard, 4 wouldn't close period. Swapped bolts, same thing with other bolt. Swapped back, same.

Considering how thin a burnished down piece of Scotch tape is, I'd say that's a pretty sensitive indication and that it's good to go.

-Scott

[Devil Dog]

Scotch tape is one way. Another way is to full-length size a case in YOUR die. Insert a FIRED primer into this case, but do not seat it all the way. Leave half of it protruding. Gently close the STRIPPED bolt on this case then measure how much primer is now protruding. That will give you an idea how much clearence YOUR rifle has with cases resized in YOUR die. It wil not tell you if your rifle will pass a headspace check. Only gauges will tell you that.