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7.62 vs. .308


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Great info on my question about the difference between 5.56mm and .223 Remington ammo - thank you.

 

All that got me to wondering about another dumb question:

 

Is there any difference between 7.62mm NATO and .308 ammunition? I have always understood them to be the same, but in light of what I just learned about the 5.56/.223 I wonder if that assumption is also incorrect.

 

What's the verdict on this one?

 

All info greatly appreciated.

 

Steve

Collecting 3rd Armored Division items of all kinds from all eras, specializing in the 36th Armored Infantry Regiment.

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I pulled this off the web.

 

OK --- Let's address the oft-posed question "Are the .308 Winchester and 7.62x51 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 7.62x51 max is 50,000 psi. Also, the headspace is slightly different. The .308 Win "Go Gauge" is 1.630" vs. 1.635" for the 7.62x51. The .308's "No-Go" dimension is 1.634" vs. 1.6405" for a 7.62x51 "No Go" gauge. That said, it is normally fine to shoot quality 7.62x51 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 7.62x51. So, you should avoid putting full-power .308 Win rounds into military surplus rifles that have been designed for 50,000 psi max. Reloaders should also note that military ammo often is made with a thicker web. Consequently the case capacity of 7.62x51 brass is usually less than that of commercial .308 brass. You may need to reduce recommended .308 Winchester loads by as much as 2 full grains, if you reload with military 7.62x51 brass, such as Lake City or IMI.

HHC 3/39th Inf. Bn., 9th ID 76-79
IAFF L-726 - retired.

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Just like the other thread, fire what is marked on your barrel.

 

Excellent advice and that's usually what I try to do, but every now and then you get a deal.....

 

Better to know the differences than to remain ignorant, so I'm glad I asked.

 

Thanks for the advice.

 

Steve

Collecting 3rd Armored Division items of all kinds from all eras, specializing in the 36th Armored Infantry Regiment.

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I'm not a reloader, so I'm more interested in off the shelf commercial .223 and .308 vs. surplus 5.56 and 7.62 NATO.

 

I am not a target shooter either, so I go with what is most inexpensive, but have so far avoided the steel-cased foreign stuff.

Collecting 3rd Armored Division items of all kinds from all eras, specializing in the 36th Armored Infantry Regiment.

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