Haha! Sounds like a sales pitch to me!
I currently load my 45-90 with 18.5 grains of Trail Boss and a 405 cast bullet.
People think I am a real tough sombitch and everyone likes seeing that Winchester yard that big ole case out of the action.
Honestly, I cant shoot much more than that due to the shape of the stock.
It's almost apples to oranges here. I assume your Winchester is a Model 1886. There were likely NO 1886's used on the Buffalo prairies since they're too new. There were likely a few 1876's, but they simply weren't the gun a Sharps or Rolling Block is when it comes to Buffalo killing. Much of this is about history and getting a feel for what it was really like shooting Buffalo for hides.
I've owned an 1886 in 45-70. It started out life as a 40-82 but was re-bored for some reason. It was an excellent gun, but not a traditional "Buffalo Gun". The 45-90 is more of the same.
I've got an 1876 in 45-75. The 45-75 isn't as powerful as the 45-70. The guns the cartridge is made around won't fire the heavy bullets a 45-70 will. A 405 grain bullet is the standard bullet for the 45-70. Shooting that with 20 more grains of Ffg would certainly flatten a Buff, but it's not all about the kill. See Gunner's posts.
I keep most of my guns in the safes but I have some guns out that I use. My 1876 is setting in a corner of the mud-room and the ammo is right here beside me on the Printer. 350 grain cast bullet with 4759 powder under it. Packs a wallop but isn't my Sharps.
