I do not know if you own a 45-70 or not, nor do I know if you have ever shot bison, but my offer still stands.
I have a 45-70 I can loan you (if you don't have one) and you can shoot whatever ammo you deem necessary (as long as it is safe which Garrett should be). You can then use the rifle to harvest a bison with us this fall. These are "wild" bison in that you will not be able to just walk up to them and shoot them. With this scenario you would be hunting with a 45-70 along side at least one (probably two) 50 caliber African stopping rifles. You would be able to see first hand what the difference between a 45-70 and a true blue African stopper really is. I suggest that only broadside double lung shots be taken, as this will truly seperate the "men from the boys" (CNS hits are the great equalizer). I'll even let you take the first shot and anchor the herd (if you hit a bison that is) so that you are not "handicapped" with shooting an adrenalized animals (they get rather pumped up after the sh t hits the ol' fan). I did mention this is herd hunting, not that crap on TV where they shoot solitary bulls (much more difficult and potentially exciting). Herd hunting also makes it more difficult to find your animal if you haven't hurt it REAL bad with the first shot.
This approach is a whole lot cheaper than going to Africa and learning.