I don't know a whole lot about African rifles, but I looked into them for a while, and a couple places I came across made references to the .458 Winchester sometimes lacking in penetration, and that many PHs prefer the .416 Rigby for deeper penetration and controllability. I don't know how accepted that notion is, but I've gotten the impression that a lot of the larger African calibers increase diameter at the expense of sectional density/penetration. It may or may not be a real issue (never been to Africa), but I figured I'd mention it since your life may depend on it.