I have three 308s, two kimbers and an old Remington 722. Everything dies on schedule when hit properly.
The 300 is for elk mostly. Although I can and do hit the 450 yard gong with my 308s, the 300 WSM or 7mm WSM allows a sightly greater margin of error (+- 75 yards) over the 308.
That being said, the longest shot I've ever taken on a game animal was 353 yards (measured), and can't imagine taking one much over 450 for any reason.
