The 338 win mag is a fine and powerful cartridge, and will add a little insurance over any 300 mag. The 300's will likely do a good enough job of any game in north america, provided tough and heavy bullets are used. I would feel at ease with just my 45-70 and some heavy cast LBT type bullets at 1800-2000 fps. They will out penetrate any 338 or 300 , and break more bone while doing so.