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Discussion Starter · #1 ·
According to my SA invoice my headspace is 1.6315. Is this ideal for shooting both commercial and surplus ammo? What is the ideal headspace, I've heard some say that it was 1.632 and some say 1.634. What is the best number to shoot both types of ammo?
 

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I've heard 1.632 for match. Your pretty close to that now. Military firearms are cut long in the throat so they go bang every time even in less than ideal conditions: mud, sand, dirt or water. You should be fine with any good ammo.
 

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Minimum headspace for the M14 Rifle is 1.634".

There's an out of battery firing thread on AR15 dot com with a short headspaced M1A and military 7.62mm NATO ammo.

With a rifle as short as your's I'd want to hand cycle "surplus .308" ammunition into the rifle to ensure the bolt closes all the way. Strip and reinstall the bolt. Assemble the oprod but no spring. See if the bolt will close on the cartridge by the tip test using just oprod weight.

Millions of 7.62mm NATO rounds are converted annually to .308 Winchester by the exotic conversion procedure of slapping .308 WIN labels on the boxes so there's little chance of any problems though.

-- Chuck
 

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Discussion Starter · #4 ·
Well I just picked up the Kuhnhausen book today and he states that the headspace should be between 1.631 and 1.632 to ideally fire all ammo. But some have said 1.634 like you Chuck.

What's the discrepancy here?

I have already fired over 1,000 rds of surpus ammo and about 50 rounds of commercial. The commercial ammo actually seemed to fit tighter in some instances. Never had any apparent problems with either.

I was just wondering after reading that thread of the KB on Amback. I do have a USGI barrel though, so does that mean that my chamber more readily accepts military ammo?

I have noticed something very interesting from SA. The manual that came with my rifle I believe suggested to fire commercial .308 ammo or good qaulity 7.62 NATO military ammo. HOWEVER, if you look at the manual that they have now online for the M1A it states that qaulity military ammo should be fired or commercially produced "7.62" ammo, it does not say .308 like it does in my manual.
 

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The difference is between the NATO (military) and SAMMI (commercial) headspace specs.

Your rifle is headspaced to the commercial spec, not the longer military spec. You should be good to go for both commercial & milsurp ammo though.
 
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