Stone and Pete have both given good advice, but I'll add that all African game are considerably tougher than game from the western world, probably because of the high predator pressure and zebra and wildebeest are probably the two toughest game animals in Africa on a pound for pound basis. Shoot 'em even slightly wrong and you can walk after 'em for days..............
Regarding the bushbuck. They're solitary and secretive animals and in most places, don't have an overpopulation problem. With herd animals such as impala, you'll usually cull 'em on the lamp with head shots and shoot big numbers or in some places such as the cape, they'll drive 'em past the guns in a similar way to driven pigs in Europe.
Because bushbuck are solitary, you don't get to see many of them so you won't cull many and in most areas, they rarely need culling anyway.
Bushbuck incidentally are extremely habitat dependent. For example in areas such as the SA/Botswana border, the overpopulation of Elephants mean the Elephants come to the dense riverine habitat to feed on a regular basis and as they feed, they destroy that particular habitat, which means the bushbuck females are forced to move their young back further from the river into less dense bush, where the baboons can get to, and kill they young. - Hence over a period of time, too many Elephants, means less bushbuck and more baboons.
Going back to Pete and his 300 WM, he shoots the thing like a laser and if there's any one person I'd be happy to let shoot a big animal with a small calibre, it's him........
I'd probably want him to use his zimmer frame as a rest though!