I always enjoy venison for dinner on Xmas day whenever I can bag some. Well, I hear some reindeer will be coming by my place on Xmas eve. So I’m wondering…
Although .308 Win and 7.62 NATO may have identical size bullets and cases, the charges (and therefore pressure generated) are not the same. Can I safely fire .308 Win from a bolt action chambered for 7.62 NATO?
Looking at the Wiki articles, the .308 runs 62K vs. 60K for 7.62.
Ah, so it’s the other way around. Then I can shoot 7.62 NATO from a .308 bolt action rifle.
It’s backwards compared to shooting civilian .223 in military 5.56x45mm, but not vice versa, if that’s what you mean. From what I understand, the dimensions aren’t exactly the same, so I think they headspace differently. FWIW, I have shot store bought .308 in a rifle marked 7.62x51mm (Ishapore 2A1, pretty much an Indian SMLE in a different caliber and bigger magazine) with no ill effect. As a complete WAG, meaning please take it to a gunsmith if you’re worried, is that a bolt action will be better, and ammo will be fine especially if you buy regular rounds and not the more expensive ones that are high velocity or whatever
From the firearms blog - note that 7.62mm pressure is 50,000psi vs 62,000psi for the.308.
"Before we go much further, we want to address the oft-posed question “are the .308 Winchester and 7.62×51 NATO one and the same.” The simple answer is no. There are differences in chamber specs and maximum pressures. The SAMMI/CIP maximum pressure for the .308 Win cartridge is 62,000 psi, while the 7.62×51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win “Go Gauge” is 1.630″ vs. 1.635″ for the 7.62×51. The .308′s “No-Go” dimension is 1.634″ vs. 1.6405″ for a 7.62×51 “No Go” gauge. That said, it is normally fine to shoot quality 7.62×51 NATO ammo in a gun chambered for the .308 Winchester (though not all NATO ammo is identical). Clint McKee of Fulton Armory notes: “[N]obody makes 7.62mm (NATO) ammo that isn’t to the .308 ‘headspace’ dimension spec. So 7.62mm ammo fits nicely into .308 chambers, as a rule.” You CAN encounter problems going the other way, however. A commercial .308 Win round can exceed the max rated pressure for the 7.62×51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max. - See more at: .308 Winchester vs. 7.62x51 NATO -The Firearm Blog
Also see this discussion of the difference between .308 and 7.62, primarily dealing with chamber dimension differences between military rifles chambered in 7.62 X 51 and civilian rifles in .308 Win. Cliff’s: the military rifles often have a larger chamber dimension, which, when coupled with thinner civilian brass in .308 and higher pressure for that round, may lead to case ruptures. That would be bad.
The Gun Zone also weighs in on the differences. Aside, it’s a pretty old article if it mentions the law firm of Brobeck, Phleger and Harrison. Still, it mentions an update in 2009.
Interestingly, the first link I put up mentioned that the pressure specs for military 7.62 was 50,000 CUP. Not PSI. In PSI, that would be ~58,000. For .308, as noted, the pressure has a SAMMI max of 62,000 PSI. So, somewhat close to each other, if indeed the 50,000 was referring to CUP (Copper Unit of Pressure). The typical proof loads for both are vastly different however. I am curious whether the pressure spec of 50,000 for 7.62 X 51 mm was originally in CUP or PSI. Wouldn’t be the first time a units confusion led to hilarious results.