I get to hunt in some bear country, black bear and grizzly. Minimum carry weapon for me? .44 mag. That and a can of bear spray, of which I am more likely to use the spray first as it is going to cover more area than a quick-draw shot.
.40 S&W or .45 ACP? No way would I count on those to stop a bear. Sure, you could get lucky and make a kill shot with one, but I'd rather have the gun that Dirty Harry said would crack an engine block.