Some time ago I saw a reproduction of a Winchester cartridge list from 1910 or thereabouts. The BP 50-140 was listed, as well as the .30-06. Those cartridges tied for highest ME. For perspective, remember the 1910 .30-06 was about equal to the modern .300 Savage.
Those rifles will kill bison. As a matter of fact, Howard Hill killed a bull from horseback with a broadhead, as did a lot of other people 100+ years before him. My ancestors here in Missouri exterminated them with muzzle loaders before BPCR were invented. But the BPCR are wimpy compared to "modern" weaponry like the .375 H&H.
The editor of Rifle took a lever-action 50-140 with BP loads to Africa a few years ago, and killed a cape buffalo with it. He chased the poor thing around for an hour, shooting it something like 14 times before it died. His buddy, who also writes for Rifle, took a .45-70 with hot smokeless loads and did a whole lot better, so much so that he didn't use the .375 he had along for insurance.
When we shoot BP, we are stepping back to the past. Not so far back as the atal-atal hunters or even the archers, but back.
