Headspace Worries


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brianr23
November 15, 2007, 10:42 PM
I purchased a 7.62 Nato Israeli Mauser. In the interest of safety I took it and had it headspaced. The extractor was removed and bolt partially disassembled before the test. The smith used a .308 field reject for the test. The bolt started a turning motion but did not completely close. He told me the rifle was probably not safe to fire. The field reject gage was 1.638". After doing a little research I have found that 7.62 Nato has a 1.640" no-go and a 1.645" field reject. Based on the bolt not completely closing on 1.638" it is entirely possible that the rifle is within the Nato no-go specs and well within the Nato field reject. Based on that I think the rifle should be okay with Nato ammo but not commercial .308 ammunition. Am I wrong? Any opinions, advice or help would be welcomed.

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highorder
November 16, 2007, 01:11 AM
were the chamber and guage spotless and very lightly oiled?

brianr23
November 16, 2007, 07:07 AM
The gages were cleaned and in perfect shape. I am very confident that the test was done correctly. As to lightly oiled, I can't say for sure but lets just assume that the test was done correctly.

rcmodel
November 16, 2007, 12:26 PM
If the bolt wouldn't close on the gage your gunsmith used, the headspace is less then 1.638", much less then the NO-GO 1.640" and probably well within .308 headspace specs.

Just because it will only "start to close" on a "field reject" gage doesn't prove anything at all, except that the headspace is well within limits.

My advice would be to shoot it.
At the worst, you will experience incipient case-head separation, or complete head separation.

Neither one is particularly dangerous.
You just can't use the brass for reloading again.

Years ago, in the days of brittle brass, head separations were a common occurrence. They always break well inside the chamber, always continue to provide a gas seal, and at the worst, you will need a broken case extractor or a bore brush to get the broken case out of the chamber.

Back then, the armys of the world issued broken case extractors to the troops to deal with it, and keep right on shooting.

And don't get caught up in the 7.62 NATO/.308" thing.
You have a 98 Mauser, not an FAL or M-14.
It will not care one whit whether you are shooting 7.62 or .308 in it.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

highorder
November 16, 2007, 02:32 PM
rcmodel has it right!

brianr23
November 16, 2007, 08:37 PM
He did the test with the .308 no-go and it did completely close on that. So it is somewhere between the no-go and field reject for .308. I appreciate the help. I will start with nato spec 7.62mm and see how that goes. Unfortunately I wont be able to shoot until after Thanksgiving.

Jeff F
November 17, 2007, 10:13 PM
.308 and 7.62 NATO head space guages are not the same. I have a couple of 7.62 NATO bolt actions that close on a .308 field reject guage and are perfectly safe to shoot.

mejeepnut
November 18, 2007, 12:39 AM
I just don't undersand this one at all,If its a 7.62 Nato chamber then use 7.62 Nato gauges.If its a .308 chamber then use .308 gauges.I don't know the differance between the 2 but if there is one besides the extra 10,000lbs or so of preasure that the .308 has over the 7.62 Nato then let us know!Use the guages that have the same markings as the gun!!!!!!!

jacobhh
November 21, 2007, 05:22 AM
Re-read RC's post then go shooting.

I'll bite my tongue.

Marintime Mike
November 25, 2007, 03:33 PM
I just bought an Australian International Arms upgraded Lee-Enfield , called an M10 B1 ( which is the sporterized version ) chambered in 7.62 NATO.
The manufacturer advertises it as 7.62 X51mm NATO ( .308 winchester ) as though they were completely interchangeable...The action is considerably strengthened ( About 1 1/2 times thicker then the original Lee enfield ) and is built to withstand higher pressures...I took the thing to what passes for a gunsmith around here and the action would close on a SAMMI GO guage,,,and not QUITE close on a Field reject for .308.....It took a live round and came out without any marks on the cartridge....my "gunsmith" thought the headspace was actually '"tight" on the GO guage..I am fairly confident that I can use commercial .308 in the thing....If I can lift the rifle that is...it has teak wood furniture and weighs a ton......but it is a lovely looking thing...Check it out at Australian International Arms....Any comments on the safety issue ?....I don't mind a jammed cartridge...but I don't want the thing self dismantling three inches from my face...

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