I've been a guide the better part of my life, guiding every thing from elk, and cats to bear. In the lower 48 my side arm has always, and always will be a shotgun. Occasionally a .45-110 custom lever gun. For Alaska I had a local gun guru build me a custom .378 Weatherby. Firing 270 grain Truncated solids, or 300 grain round nose puts me at around 5,700 Fpe, and 3,000 fps. Now if this gun was not a hand built rifle, I would not trust a Weatherby's action. But I have no problem carring this gun into the nastiest of conditions. And will have confidence in it on my next trip to africa.
But ideally here are my top picks.
.458 Lott
.450 Dakota
.458 Winchester
.375 H&H
.400 Whelen
On my last trip to Africa, I carried the .450 Dakota. Never had a reason to use it as a bad situation ending weapon, but I did have a chance to try it out on various plains game. And I was very impressed.
The .458 Winchester is under rated as a dangerous game gun, namely because of the old power and bullet loading from its early years. In todays powders, this gun can push out well over 5,000 Fpe. And that my friends will put down whatever walks this earth......or ever has.