It's a tricky question... Hunting how? Hunters on a Safari, local hunters, PHs all have a different relationship with the game and hunt. Then there are the bloody statistics, pretty much inexistent: it's very difficult to say how many of these are hunted vs how many of those, and how many casualties ensued compared to the number of animals involved.
Now, for a cursory, and personal, reckoning based on a solid thumbsuck, lots of campfire talks, and the help of respectable quantities of high quality spirits - and the occasional moonshine. Worth the entire amount I charge for it...
Buffalo will take the most hunters, but this could simply be due to the sheer numbers hunted. Buffalo has an interesting character: although it rarely charges unprovoked or even when shot, once he's wounded he'll hide somewhere, get very seriously crossed at you - and wait for you. When he comes for you, nothing will change his mind. There is no "turning a charge" with a buffalo: you kill him, or he kills you, period.
To add to this, once the adrenaline sets in, he can soak bullets in an incredible way. Absolutely mind boggling. As one of my mentors, who's been guiding for 50 years or so, succinctly put it one evening that we were discussing the various ways buffalo keep life interesting for hunters: "With buffalo, if the first bullet is not good, the next fifteen are useless..."
Hippo is the biggest killer - of natives. Mostly fishermen, who constantly risk their ire, happily paddling in totally unstable and shoddily made canoes. Males are territorial, females are very protective of their calves, and these critters can chew a canoe down the middle in one bite. Their teeth constantly rub against each other and are as sharp as a razor: a hippo biting you is bad news, he'll cut you in half. If you're lucky, you'll end up with wounds that you'd need a football to plug. Seen fishermen after the match, and it ain't a pretty sight. I haven't seen one who was still alive, but I have pictures...
A wounded leopard must be followed (like anything else, mind you...), and when found it will charge, that's a given. A buzzsaw on PCP, jumping from one member of the party to the next. But more victims are badly shredded than killed. PHs don't really like going after a wounded leopard, and often wrap themselves in thick leather and whatever they can find to protect strategic areas. Many use a shotgun with buckshot for that, because the shot will be close and fast, and leopards are not really tough animals compared to the other dangerous game.
Lions are not killers: when they catch a prey, they are perfectly content to hold it down and chew it alive. Then, they usually concentrate on one fellow in the party, so while the lion is busy chewing you, or your brother-in-law, someone else has a good chance to shoot him off your rib rack. People killed by a lion are usually alone when they meet, or with an unarmed party. Also, their aggressivity towards man depends on the area they're from. In some places there are almost no cases of man-eating lions, while in other areas they have a long tradition of picking on villagers.
Elephant... Well, when you have something that looks at you from the level of a first floor window, weighs ten grands or more in pounds, has a 7 foot appendage the size of a telephone pole in lieu of nose, and is smarter than your average Alsatian, you don't want to be on its list of unfriendlies. Elephants are humongous, they can go through a thicket of young trees just as easily as you walk a golf course, they have an incredible sense of smell, and they are probably the most intelligent land animal outside of the great apes. They will actively hunt you if they hold a grudge against you, especially the females. Granted, one bullet in the right place and they are down - like anything else, but as far as I'm concerned, that's the animal I give the most respect when I'm on his turf.
Now, rifles... For the rifle itself: reliable, simple, reliable, sturdy, reliable. And, if at all possible, reliable. You'd be surprised how many rifles you can throw in the dumpster just for that little word, reliable. It has to unlock, open, feed, close, and go Bang! EVERY time, no matter how fast or how slow you slam the thing. No hiccups, no binding, no FTE, FTF, or W.T.F. at all.
As for the caliber... Not going to start a debate on calibers here, that would be unheard of on this forum
. When hunting, the caliber matters much less than bullet construction and shot placement. A quality bullet in the right place will kill anything. I'll take a good shot with a 6.5 over a bad shot with a .500 any day. The best one-shot kills I've seen on buffalo were with .300s, and the worst clusterfcukks were with .450-something. The .300s shooters were seasoned hunters, who had done quite a lot of mountain sheep and goat hunting. The "wish I hadn't come here today" cases were gents who had bought a BIG-friggin'-expensive Safari rifle that they couldn't handle, and must have put the grand total of three rounds through the darn thing, eyes shut and shoulder moaning in anticipation.
When backing up someone else, or following big things in thick stuff, this is where you want something more specialized. Heavier bullets, that keep their shape, don't blow on bones, and penetrate straight and deep. .40" and larger, 400 grains and up, 2100-2400 fps, these are the usual recommendations. This is due to the fact that you'll have shots from any odd angle, at speed, on something moving, and sometimes without even seeing exactly where you are shooting at. You want to punch big holes, break things, and go through a lot of meat, bones, and whatever there may be in there.
