Yes, I was familiar with the Army Ammo Data Sheet. I had read somewhere (can't find it now) that this was from an early draft and it just "stuck" while the most common bullet weight used was 124 gr. This post from another forum seems to confirm it -- he pulled the bullet and it weighed 123.6 gr.
http://forums.thecmp.org/showpost.ph...4&postcount=13. As I said, I can't confirm it and it's not a big deal either way.