East of the Mississippi...I'm comfortable with a 180 grain cast load, in .357 magnum, from Buffalo Bore as it would be sufficient, as would 10mm, .44 magnum, and .45 Colt +P, or .454 Casull!I have hunted black bear in Maine four times and have taken three bears. I would consider a .357 Mag loaded with a heavy bullet to be my minimum suggestion for black bear. I would feel confident carrying my S&W 681 loaded with either Garrett or Buffalo Bore ammo.
West of the Mississippi...I'd stick with the .44 magnum, a 10mm, or .454 Casull!