I have looked at SOME of the guided hunts regarding bear.
Most ALL of the outfitters will tell you that the .44 magnum is the very SMALLEST load you would want to use. I've seen stories written that say some have EMPTIED a 6 shot .44mag in a bear, and it kept coming!
I would NOT go with anything smaller than a .454 a .500 would be better.
The outfitters I looked at suggest a .44mag as a BACKUP gun!
I would suggest a Ruger .44 magnum Super Blackhawk with some heavy loads. Depending where you place your shot...it should be no problem. Whatever you decide....get lots of practice shooting it.
i have 44 taurus tracker was my only carry gun for 2 years carried hiking in the northwest to the grocery store every where i found that i carried it when other people left theirs in the truck and very comfortable to carry to due to smaller cylinder i have never had a problem with it