One report says the Southern Herd was hunted heavily from 1874 til 1878, the Northern Herd from 1880 til 1884. In 1882 there were 200,000 hides shipped out of the Dakota Territory. Ten years and there was scarce a buffalo to be seen. That was government policy, to impoverish the Plains Indians and make them dependent on reservations.
In the 1870s, before the .45-70 got on the market, the Sharps and Remington .44 calibers were popular. There were a good number of .50-70s available as surplus replaced by the 1873 .45-70 and commercial, too. Buffalo Bill Cody's favorite rifle was Lucrecia Borgia, a .50-70 Trapdoor Springfield.
But in the late years of buffalo hunting, the Sharps Rifle Company announced that the .45 caliber had proven so superior that they would quit making .40, .44, and .50 rifles except on special order. Not all were .45-70, (As loaded for Sharps, it was really a .45-75) though. The .45-2.4", .45-2.6", and .45- 2 7/8" were popular. (.45-90, .45-100, and .45-110 in Winchester parlance, although the powder charges were not standardized at that, so it is safer to refer to them by case length, the .45-70 being .45-2.1")