[ArmySGT.]

Originally Posted by welsh

Hey Sgt-
My mistype sorry. I am thinking of .308 cartridge or 7.62 NATO round. My bad.
http://en.wikipedia.org/wiki/.308_Winchester
http://en.wikipedia.org/wiki/7.62%C3%9751mm_NATO

Had not even been thinking of the .30-06 cartridge.
I can see the advantage of the greater ammo load with the 5.56. I am guessing availability is about the same. But quality?

Ah, Similar dimensions, different SAAMI specifications.

Shooting .308 winchester in your 7.62 NATO battle rifle is possible..... However in older rifles you could run into problems.

.308 Winchester has a CUP pressure of 62,000 pounds whereas, 7.62 NATO is loaded to a CUP pressure of 50,000 pounds.

In 90s vintage M14s or AR-10s with 90s era metallurgy probably not much other than different points of impact due to different velocities.

has been known to bend operating rods, shear extractor pins, and damage bolts of 60's era M14s.

Same can happen shooting heavier bullets. 7.62 NATO uses a 150 grain bullet. .308 Win comes a variety of flavors (aka heavier and lighter bullets). Also sometimes with heavier bullets you get a longer overall case length which creates failure to feed problems in autoloaders.