Let me offer you this: When I have a question about which caliber or bullet will do what, I go into my reloading room and pull down one of the manuals off the shelf. Reloading manuals are one of the greatest sources of ballastic information and comparison that any shooting sports enthusiast could ever hope to find.
Sounds like you need to find someone who actually owns these rifles and get him (them) to let you take a few shots. Quite frankly, if I lived in Africa, I'd be looking to carry as much rifle as I could find. Don't forget Jeff Cooper's classic remark about African hunting rifles: 'The right caliber always starts with a four!'
(So matt g. is right!)