You can't do better than a 308 Win. Thirty caliber energy with knock down power and accuracy that is next to none. Most sniper or tactical applications are in this old, but trusted round. You don't need a magnum firearm to make long consistantly accurate shots. I don't know if it's a macho thing or what to say, I shoot a ---Mag. Big deal! Unless your after big game, I mean moose, brown bear or dangerous African big game. You don't need any more knock down power than the 30 cal. 308.
Good Hunting...