Are you thinking of Karamojo Bell Cole? I always associate Teddy Roosevelt with a .405 Winchester M1895, although he used an English 500/450 double rifle too on safari, that presumably being his elephant rifle.
Bell killed hundreds of tuskers as a professional ivory hunter with the 257 Mannlicher (6.5X54MS), 275 Rigby (7X57 Mauser) and 30-06, and no doubt a few other calibres too with short-range and very precise brain shots that exploited a weak spot in the animal's skull. With his knowledge of the pachyderm's skeleton and skills, he could probably have managed it too with a .22LR rabbit gun if he'd decided to be really radical!
For every such Bell who performed these feats, there were thousands who couldn't including some who tried, failed and died as a consequence. Never heard of Razor Dobbs, but if that was a 10mm pistol on cape buffalo, that sounds to me like another near Bell-type unique character who performs feats that are suicidal for 99.99% of even the most experienced DG hunters. Likewise sticking to handguns, there is probably only one Jerry Miculek on the planet.