If I was in the back country in Alaska and I were only going to carry a pistol it would be a 44 mag or bigger. Outside of Grizzly country I would cary what I was comfortable with. A revolver is just fine. I prefer Autos and carry a Sprinfield XD Tactical 45 for my back country pistol. I carry it on my hip and it does the trick. Open carry is legal here.

Any pistol is not going to be a magic bullet. Shot placement still counts and hitting a PO'ed black near is harder than it may sound. There may be issues with penetration etc. But 40 cal and 45 10mm will do the trick in an auto if you do your part. 357 and up will also do the trick if you do your part. All will do the trick on lions, bears and two legged critters.