Do you want a 50-90 in a single shot or a lever rifle?
I really like that lever rifle I have in 45-90.
The only way to go is the Shiloh Sharps model 1874 although I believe Pedersoli now makes their 1874 in 50-90 and would be several hundred dollars cheaper. The quality of the American made Shiloh will be worth the extra money. Both these guns are replicas of the big buffalo rifles used to do in the Bison herds from around 1868 to about 1884 with the Montana herd being the last to go. The Winchester 1886 was never used for this because it was not around when there were significant numbers of Buffalo. Even the Winchester 1876 was late to the game and more of a hunter's gun than a market hunting gun. The '76 was chambered in rounds big enough for Buff but not approaching the size of the Sharps cartridges. I expect some were used, but nothing extensively.
The Buffalo hunt started in Kansas with converted Civil War Trapdoor Springfields in 50-70 and Remington Rolling Blocks. Soon the Sharps Conversions were the darling of the hunt and the culmination of the Sharps for Buffalo was the model 1874. The 50 caliber was a favorite early-on but by the time the hunt moved from Kansas to Texas and up through Colorado to Wyoming and the last days in Montana, the 45 caliber variants became favored.
You can outfit a Shiloh in about any configuration you want from common Business type rifles favored on the prairies to wild setups designed to wring every last modern ounce of performance out of a given cartridge.
