It actually has a lot to do with the ammo. In fact, it’s probably a close second to shot placement. Even with proper shot placement hollow points just don’t do as good a job at breaking bones and penetrating. None of the “experts” that I know of recommend hollowpoints for bear defense. John Linebaugh, Tim Sundles, Ashley Emerson all emphasize the importance of using a tough, deep penetrating solid.
I'm operating under the assumption that the context of this thread is the DEFENSIVE use of a handgun against bears. In those circumstances, just about any medium to large caliber service handgun cartridge (9mm, .357, .40, .45, 10mm, .41/.44, et al) will bring about a cessation of the attack, IF the operator can achieve reasonable hits.
If I knew I was going to use a handgun to shoot a large predator "on purpose", then yes I'd choose the most effective handgun and load available, but that's irrelevant to this discussion.