pretend we started from a clean slate. No previous rifle designs, no common brass or bullets. Few people would go for the 308. As a hunting round it's fine, but as a military round, it leaves a lot to be demanded. A slightly shortened 6.5-08 (ala 264 boston or 260 ghengis) would be a better choice imho. better ballistics, less recoil, with the right bullet, better penetration.
atek3