You don't need a special gun to kill bears. A handgun is used for personal protection when you're not carrying your rifle. If you'll ever put your rifle down for any reason, it is sensible to have a handgun. I live and camp around bears, but they are hardly my foremost concern. Still, I carry a handgun every day, not a rifle. When I go to sleep in camp, it's not a rifle that's in my sleeping bag, but a handgun. When you're camping or hunting with others, it can be another person who gets in trouble and it might be when you didn't think you needed to have your rifle. They might appreciate it if you weren't unarmed.
I suggest carrying the handgun that you're most proficient with. Personally, I carry a 357 Magnum revolver and that's what I devote all my practice to. However, it's better to be armed with a 9mm pistol with which you are proficient than to be armed with an unfamiliar gun. I would be much less concerned about a bunch of 9mm hits failing on a bear or moose than I would be about fumbling around with an unfamiliar "bear" gun with which I might manage to get off one shot that misses.
