Yeah an dif you REALLY want to impress a buffalo, try at 416 Weatherby like Layne Simpson says. That 400gr2700 really gets their attention! As to the 458, no doubt a proven and impressive killer, but it's almost like a double in that it is a specialized caliber for closer in work. There's just no getting away from the fact the 416 "Rs" are a great caliber and a lot more versatile. jorge
Now Jorge, if you really, I mean REALLY want to impress them just try the 450gr TSX @ 2550fps...guaranteed to impress you too,LOL!
2700 really gets their attention! 
As to the 458, no doubt a proven and impressive killer, but it's almost like a double in that it is a specialized caliber for closer in work. There's just no getting away from the fact the 416 "Rs" are a great caliber and a lot more versatile. jorge 