Many many years of Winchester collecting but I don't remember hearing of that round's intended use on buffalo. Teddy Roosevelt had some unkind things to say about it (preferring the original .45-75 WCF chambering in his 1876) and at any rate the .50-95 was not popular in the US.

The places typically associated with the .50-95 WCF are India and Africa. The large diameter "express" cartridge was supposed to be popular for hunting big cats, and some of the Bond Street gunsmiths, including Holland & Holland, upgraded Winchester 1876's to be sold in their shops. It's not always possible to determine a shipping destination for original Winchesters, but I wouldn't be surprised if the majority of .50-95's made by Winchester were exported.

You can buy reproduction 1876's, and possibly Lightnings, in this caliber. Mike Venturino and others have published black powder and smokeless load data.

In addition to the .50-110 (aka 50 Express) Winchester loaded the .50-100-450 with a heavier bullet & different twist barrel.