RE: 338/378 Weatherby
From most of the things I' ve read about the .338/.378 (I' ve never shot one), they are pretty tough to shoot without a muzzel brake. That' s an awful lot of gun you' ve got there! If you can tame it, I would think you should feel pretty comfortable shooting at almost anything in the world, except maybe some of the really grouchy African critters.
Good luck with that beast!