Hazcat's assertion about the 7.62 having a slightly thicker brass case than it's .308 counterpart is correct, and is mentioned in my Speer manual No. 12, which recommends reducing powder charges by 5% just to be safe.
Fulton Armory has some expertise in this matter, and their comments are HERE.
Well, we're all up to date on this one now. This is one of the things I like about this web site, one can't be misinformed for very long!
Thanks, guys!
BTW, I did mass out two cartidges and found the military one heavier...about 5% at that.