I am thinking aboutbuilding a custom long range rifle and am debating between these two calibers. I am looking a punching paper at 600 yards or so mainly but would like the option of hunting deer as well if I ever get good enough.

I realize that the militay uses the 308 a lot and its one of the most popular for extended range, but why do they use it over the 30-06? What would make it a better long range contender?