Well, with all things considered, I would have a hard time moving off that .308. With its effective range being beyond 500 yards , shooting a 165 gr. swift scirocco Bonded bullet ( 1239 ft.-lbs energy ). If you can get it there, you can kill it. And it has a very tolerable recoil. You will lose that if you change to the ultra mag. Thats a given. And you won't be gaining much in the process.

I say stay with the .308. It is a great round.