The 300 rum is a powerhouse...one of my favorites to drop huge Louisiana wild boar pigs(which are some of the tuffest game)....but if u have a 300 winny, its time to step up to the 338's. Rather its the edge or a 338 rum, both will handle almost anything u throw at them. I am building an edge, but after a little reading I would suggest the rum. Factory stamped brass(u mentioned going to Africa), and you can damn near get the same velocity from a rum that u could get from an edge just by running a long, 30-32" barrel, if the edge if running a shorter 27-28".
I bet the 338 rum or 338 edge will fill the bill