According to this AP report in the Billings Gazette, young George Clement of Belgrade was able to kill his bison with one shot.
Clement, who took the day off from school for the hunt, said he shot the bison from about 30 yards away
According to the Independent Record, citing a Gazette reporter:
Clement downed the bison with one shot from a .30-06 caliber rifle from 30 yards, then moved in close and shot the animal three more times to finish off the quick kill.
Hmm…and what in the hell is ‘quick’ about being shot four times?