RE: The 10 mm is one I looked in to as well. In the end The biggest gun
All handguns are inadequate (ok maybe the 500 S&W magnum is an exception) for bear. And any handgun round approaching adequate for bear are beastly to shoot accurately under distress. I don’t think you did too bad choosing the .45 ACP because you can shoot it more accurately under distress. But as said before you really need to be very particular with the ammunition you carry. You need higher pressure +P or +P+ to increase velocity of the projectile AND have a hard cast solid bullet that won’t deform or fragment upon hitting a bear skull.