I wasnb't there but actually, the largest percentage of Plains buffalo were killed with Sharps Carbine and rifles chambered for the .50/70 and mostly with 'surplus' US Army issue copper cased, inside (Bennet) primed, 70gr. BP loads using 450gr. pointed bullets of pure lead, running about 1,150fps from the short 22" barrels. Some rifles of course were used, giving another 100fps, but again in .50/70. The buffalo were almost done by the time .45/70 military rifles were finally hitting the 'surplus' market. the term Big .50 came about long before the .50/90 (.50 2 1/2") ever left a Sharps factory. The term was used to differenciate between the .50/70 and the smaller .40 to .45 calibre bullets.

Yes, there were a few .45/70's in the hands of market hunters along with .44/77's and a host of .40's through other .50 cal. rounds but few in number compared to the thousands of 'surplus' .50 Sharps Carbines and Rifles that were sold off my the military.

This is as I understand the way things went. I tend to look for actual documentation, letters, etc, rather than go by what modern gun writers make up and print.

Yes, the 405gr. Black Powder load at 1,200fps to 1,300fps was very effective on game. The 1880's era 500gr. .45/70 loading proved better for buffalo, elk and other 'critters or people' worth shooting at long range.