Have wondered about this for a while... Probably the best rated bear gun, especially for BIG bears, is the Marlin 1895 .45-70, especially in their short versions. That said, most people carry handguns for bear defense in everything from 9mm to .500 S&W because of the convenience of size, portability and it always being on their body, vs next to a tree or in the canoe at the time of need.
Since the Lucky Gunner study finds that handgun calibers are very effective for self-defense against bears, my question is, if you could not for some reason carry a handgun with you in the woods, like in Canada, and had to have a rifle, in this case a levergun, would you choose a large caliber like a Marlin in .45-70 or .444 or a more compact pistol caliber like .41/.44 Magnum/.45 Colt...
Thanks....Bob