You may want to check out what Weatherby has to offer. While it is hard for me to imagine that there is a North American game animal that the .300 WBY Mag can't kill, if your guide insists on a bullet diameter of greater than 30 caliber, the .340 WBY Mag greatly out performs that .338 Win Mag and the .378 WBY Mag has far more muzzle energy than the .375 H&H Mag.

Caldoc