At 500yd. a 190-grain .300 Win. Mag. has a little over half of the wind-drift as the Win. .308 does. It also retains its velocity better than the .308 at 500yd. The 190-grain .300 Win. Mag. maintains a velocity of 2,221fps. at this distance, where as the Win. .308 only maintains a velocity of 1,786fps. Obviously, this translates to more energy with the .300 Win. Mag. upon impact. At 800yd. the gap between the two rounds’ performance shows roughly the same picture. The drop for the same .300 Win. Mag. round is still just above half that of the Win. .308. The .300 Win. Mag. Now has a retained velocity of 1,860fps., which is considerably more than the Win. .308’s 1,375fps. This means that the .300 Win. Mag. is still effective to cleanly take down smaller moose at 800yd., where as the Win. .308 cannot maintain a velocity high enough to effectively expand the bullet upon impact. Just know that the .300 Win. Mag. comes with a little more kick than the Win. .308.
Though there are many different rounds to consider, these are two of the most common rounds used in North American big game hunting. The Winchester .308 is an effective medium-range round when taking on big game in North America, but you would want to upgrade to the longer, more powerful .300 Winchester Magnum when taking longer-range shots. Again, there is no one size fits all, but this should give you an idea of the different factors to take into consideration when selecting your perfect hunting