I do think this has merrit. Testing with 350gr. Speer heavy jacketed bullets as well as the 350gr. Barnes HP's in a ctg. of slightly greater capacity than the .458 WM has shown easy 350 yd. max trajectories for PG. The use of a range finder is useful for difficult terrain, but not necessary.
: In my .458 Alaskan M70, the Barnes 350"X", at around 2,500fps muzzle velocity, does just fine on our moose at longish ranges. This particular rifle puts them only 3" higher than the 500's, with 400gr."X" striking inbetween them.
: If 3" high at 100, they are zero'd at 215yd., 3" low at 250 and almost 9" low at 300yds. 350yards puts them 18" low. Aiming at the back-line of larger plains game at 350yards, drops them through the middle of the rib-cage. Needless to say, much practise at many ranges, is requisite.
: The .375 makes a much better, 1-gun battery for Africa, in my humble, lack of that experience, opinion. A well-shaped 300gr. might suffice for all game, being solid and soft as required.