In the pioneering days in Africa which probably ended by the time of WW2 a Cape in 577 and 12 bore would probably have been quite useful for a farmer or a settler. The rifle would have good for dealing with elephants, buffalo, hippos etc, with the shot gun barrel useful for birds, small buck etc. When opening the batting against a big animal you could have loaded a brenneke or paradox type bullet into the shotgun barrel which, whilst not as effective as a 577 NE bullet, would at least have given a follow up. Lion and leopard, you might have switched to buckshot instead - very effective when range is sub 10 yards.

But in the pioneering and settler days guns of any sort where expensive. Far more likely a 303 SMLE would have been taken as a rifle along with some form of cheap but robust Birmingham and Belgian made box lock or hammer 12 bore double.