if i were using a 308 for hunting, it would be sighted zero at 200yds. with a 200yd zero, there is no need to aim low, or high out to about 250yds. puts you about 2.5" high at 100, about 11 low at 300. for deer or smaller animals the 308 even with short barrel velocities is plenty powerful out to 300, with proper placement it is enough for elk and moose too, though on the edge of underpowered. the key at the longer ranges is PLACEMENT.
my ar-10 is currently sighted at about 200yds, i bought it for long range coyote hunting and intend one of these days to actually use it for that. when you start to look at long range ballistics (over 500 yds), the 308 doesnt look so good. the drop of the bullet in the 500 to 600 yd range is dramatic. range estimation has got to be right on, equipment has to be top notch, and shooter skill has to be great. even with all that, a coyote size target is a very tough shot. a man size target at that range in my estimation is easy.
since i am a long range type shooter i want the most i can get out of a caliber for trajectory which is why i have a 24" barreled ar-10, and a 26" barreled bolt rifle. both shoot the same load into one ragged hole, if i really need to shoot something flatter, i will get out a different caliber.