I've only taken 19 elk, but if the kills by friends and family at our camp are tallied up they are 80 or so. Good bullets of medium to heavy weights, from any reasonable cartridge, and placed well will kill any elk without drama in my experience. Some of the quickest kills I've seen have been with the little 7mm08 and 140 core lokt bullets. One of the most surprising "failure" was a bull I hit on the point of the oncoming shoulder with a .375 H&H and Nosler 260 partition. Bullet failed to penetrate. Most of our elk have been taken with .308, .270 and 35 Whelen. But we don't shoot at elk more distant than 300 yards, usually much closer. We just stalk closer or call more or wait for a better shot. Most of the perceived "need" new elk hunters have for a flat shooting magnum with a big scope and turrets and range finder is marketing hype and pairs well with perceived entitlement. They believe that any legal elk they see should be an opportunity to shoot - not an opportunity to stalk closer or wait for a better shot.