The case may be short compared to others, but capacity is more than you might expect, depending on how far out you seat the bullet. Some interesting info here:

https://bigborefan.wordpress.com/tag/ruger-no-1-45-70-improved/

Also, as to the Old West bison hunting, keep in mind buffalo were shot from a safe distance of 200+ yards on the open plains, mortally wounded and allowed to slowly bleed to death in the hot sun before being tracked down and skinned. One-shot kills perhaps but not instantaneous, humane stops. The cape buffalo you shoot inside of 50 yards in Africa will likely eventually die from one shot as well, even if misplaced, but perhaps only after escaping into the jess bush, or worse running you over in the process LOL.

You guys have forgotten more about dangerous game hunting than I will ever know, but again, I think there is a big difference between killing and stopping. Accomplishing the latter with one shot requires a big wallop in the right place.