The american bison was almost put into complete extinction by the colt .45
What??!! Where in the world did you come up with that? Were you thinking of the .45-70 rifle? I am sure there were buffalo killed with the .45-70, but the main gun used to nearly eradicate the buffalo was, as Art said, the various calibers of Sharps rifles.
(Luke 11:21 KJV) When a strong man armed keepeth his palace, his goods are in peace:
(Luke 22:36 KJV) Then said he unto them, But now, he that hath a purse, let him take it, and likewise his scrip: and he that hath no sword, let him sell his garment, and buy one.