Morons use target bullets (I don't care what Berger calls them, section one and learn)
Ethical hunters use strong bullets like those mentioned above. I would add any of the monometals to that list as well.
I have not hunted in Africa, but it will be a VERY unusual circumstance that would have me shooting over 300 yards at any big game. Wayyyyyy to many variables to wound a fine animal. 50-100 yards is hunting, 300+ is target shooting using live targets.
Seen far to many 3 legged Antelope, gut shot deer eaten alive by wolves, and the remains of Elk hit in the wrong place with an insufficient cartridge/bullet.
If you can't get it done with a 30-06 and 165 gr TSXs perhaps you should not try it.