Buffalo rifle

Buffalo rifle generally refers to large-calibre, generally single-shot black powder cartridge firearms which were used to hunt the American Bison (or "buffalo") to near-extinction in the late-19th Century. Three types of rifles in particular were used by professional buffalo hunters, namely the Springfield Rifle, Remington No. 1 otherwise known simply as the Rolling block, and Sharps rifles. The Sharps was the favorite among hunters because of its accuracy at long range.

...
Wikipedia