A 308 is a great gun. I would put it up against almost anything and it do just as good if not better. The ballistics on the 308 is almost identical to the 30 06. It has excellent knock down power and is very accurate.
If you are going to be having shots at the 400+ yard range, I would condider the 7mag or the 300. Very accurate at longer distances!
There probably is a good reason why snipers use 308's!
