2 reasons, though a Winchester would be OK in my book:

1. A mauser extractor isn't going to break when you have something big and angry bearing down on you. Remington extractors are very reliable on standard chamberings but have been known to break on magnums.

2. Controlled Round Feed action- A claw extractor on a Mauser or winchester won't allow a double feed type of jam which can happen under severe stress. The downside is that a rifle has to be correctly fitted for it to work- military mausers are commonly rechambered for magnums, especially the .458 WM, if its done by a garage gunsmith that doesn't know the intricacies of mausers, the rifle can jam up tight when feeding from one side or other of the magazine.

I probably will go to Africa before I get too old, but it won't be for any dangerous game, a 30-06 will suffice for what I'm looking at doing.