Plenty of experience against Aussie buffalo, none in Africa, but I can assure you it is as good a buffalo cartridge as you could wish for. My rifle has killed numerous big bulls, often as a loaner to others who want to hunt buff but don't own a suitable rifle, pretty much exclusively with 410gr Woodleigh Weldcores. One shot on the point of the shoulder is usually all that is needed to lay low even the biggest bull.

Mine killed a fine buff just a couple of weeks ago. Pic posted on 'Rodda .577/.500 takes a buff' thread in Double Rifles forum. Again here:

The rifle is not really a 'stopper' in the traditional sense, but would do the job with solids if asked. Get hold of John Wooter's articles, he killed Cape Buff and jumbo in Africa and wrote glowingly about the cartridge.

It's far and away my favourite bolt-gun chambering!