You got that right.
Preferred weapon here would be .308, 303 British or my favorite 30.06
Back in the old days they didnt call em "Buffalo Guns" for nothing.
And I would bet it did not take 120 rounds to kill 5 buffalo.
Not to forget also, Indians killed enough to feed their people, with only spears and bow/arrow.
The 45/70 Government cartridge was hell on Tatanka. I can't imagine buffalo hunting with anything under .45 (though the .44 Rem Mag might work out of a cowboy carbine).
.303 Brit,.308 Win, and .30'06 are not "Buffalo Gun" Cartridges.
The guns used to nearly wipe out bison in North America were Sharps Rifles shooting .45 and .50 cal black powder cartridges. Smokeless powder .30cal cartridges were never used in "Buffalo Guns."
Buffalo calibers were predominantly 45-70 and 50-100 blackpowder.