Surplus 7.62 in March grade chamber?

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Erickson5006

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Am I gonna damage anything by running surplus in a fancy gun, with matching grade specs? What kind of accuracy would a guy be lucky to get? (boxer primed Hirtenberger)

How about surplus 7.62 in the old 308 bolt gun? I had one casing in a dozen that was noticeably harder to extract. (rem783)
 
I think you answered your own question. military chambers are looser than bolt so they will function under a variety of conditions. too tight will create higher chamber pressures. 7.62x 51 for military, .308 for bolt. there is a ton of discussion on the differences, I won't go there. lots of info in reloading, even if you don't reload you eill get a better understanding of what happens in the chamber when you let the firing pin go.
 
7.62 military brass also does not expand as much as commercial brass according to what I've read , so if your bolt fully closes, it should be fine but check for blown primers or other signs of overpressure. That is for using 7.62 nato spec ammo in a .308 spec chamber.
Where folks need to be a little more careful is using .308 commercial in 7.62 nato chambers, expecially if the nato chamber has not been measured for headspace.

but by and large , for a long time now, folks have been interchanging these two cartridges safely in both semi and bolt guns

as an example, one of my rifles has a .308 commercial headspace measurement of 1.632" but chambers and fires hirtenberger and South african 7.62 nato with no issues.
 
My HVA Carl Gustaf sporting rifle won't chamber 7.62X51 Norc ammo without standing on the bolt handle. I've never tried firing that stuff in it.
Chambers factor 308W and my 308W reloads no problem.

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Erickson5006 said:
What kind of a gauge should I buy to check spacing?
Click to expand...

brownells carries a large selection of headspace gauges
most folks opt for GO and NO GO gauges for the chamber they are measuring
if this is to measure the chamber of an M14/M1A type rifle you will need to disassemble the bolt.
Lots of info out there on measuring headspace.
 
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