Our bear are small.

I've killed black bear with .30-30, .303 British, 7.62x53R, .348 Winchester, .44 Magnum, .45-70 and 9.3x57.

All worked well except for the .44 Magnum except I can't really blame the cartridge per se.

My favorite is the 9.3x57. Great cartridge and the gun I use weighs 6 lbs which makes it easy to lug to the tree.