CRF bolt action .375H&H. Bought mine just for a big bear hunt (that, unfortunately, has been postponed). I, personally, wouldn't find anything short of .35Whelen acceptable, and that is borderline IMO. Other options would include .338WM, 9.3x64Brenneke, .35Brown-Whelen, .405Winchester (borderline), stout .45-70Govt. (in a Siamese Mauser, no singles for that use), .416Rigby (a bit more than necessary, but it'll do the job), .458WM (and above, but again this is more than enough). Second shot capability is paramount, as is reliability under adverse conditions, however the kill shot is likely going to present itself at some range (remember the type of terrain you are in), so you want a decent trajectory. This makes the .375H&H, .338WM, 9.3x64Brenneke, .35Brown-Whelen, .35Whelen, and .416Rigby the only logical choices, with the first 3 being near ideal IMO.
You also want to select your load carefully. I would highly recommend a well constructed expanding type bullet for the first shot, followed by solids in case the quarry turns, thereby presenting a more challenging shot that requires more penetration and most importantly a straight trajectory post-impact. I would load on the high side with magnum primers, but not exceed the maximum recommended load (or if signs of pressure are noted, slightly below signs at normal temp & pressure). This would not be acceptable for the humid, hot climate of Africa, but in the desert tundra of NA you can load a bit higher without fear of cases sticking due to pressure (but DON'T go too far).
