Re: 7.62mm .308 differences???
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">Chris, that info is incorrect...
check the current pressure standards for 7.62x51 NATO, almost the same as 308 Win (only meaningful diference is measured in a 7.62 instead of a commercial 308 chamber), it uses the same transducer location as CIP standards:
http://en.wikipedia.org/wiki/NATO_EPVAT_testing
The SAAMI does not list the 308 Win and 7.62x51 NATO in their famous list of "unsafe combinations" (but does list the 5.56 vs the 223 because they do have a different pressure).
http://www.saami.org/Unsafe_Combinations.cfm
As Don said:
"The difference is in the chambers, not the outside dimensions of the two cartridge cases. The difference pressure-wise is negligible. The biggest concern relates to port pressure restrictions of the M1/M14 platform, for which the slow burn rate powders used in most commercial .308 loads is not suitable."
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Well, it just looks like they bumped the std. Mil pressure up 10k psi to 60k and the proof pressure up 8k psi to 75k. Maybe better testing protocols and/or stronger brass?
Here are the sources for the info you stated was incorrect:
"Sources: .308 Winchester data from ANSI/SAAMI document Z299.4-1992, Pressure and Velocity, Centerfire Rifle Sporting Ammunition
7.62 x 51mm NATO headspace data from Jerry Kuhnhausen's M1/M1A shop manual.
Pressure data from TM 43-001-27: Army Ammunition Data Sheets Small Caliber Ammunition"
Obviously, there are lots of people shooting NATO 556 in commercial bolt guns without incident. Still, I'd feel safer shooting commercial 308 out of my HK91/FN-FAL than I would +556 in a bolt gun, but it's no bother for me.
Take care, Chris