Interesting conversation about bear protection. I've lived in Denali Borough Alaska going on 13 years now, here is my 2 cents...
If you can handle the .454 Casull, that would be the caliber of choice. It's a lot of recoil though and most folks can't handle it. Shoot one first. Stay away from the Glock. Go with a revolver, and buy a Ruger. In a bear charge you are only going to have enough time to get off one shot. Two if you are lucky. They don't come at you from 50 or 100 feet away, they come at you from 20 or 30. They charge when you surprise them or when a sow is protecting her cubs. A bear raiding your camp for food will usually turn tail and run when you make yourself known. I carry a Ruger New Model Black Hawk .44 Magnum. I prefer the single action black hawk to the double action red hawk for two reasons: Firstly, the single action makes you slow down. That first shot has to count. Secondly, the single action can fire hotter loads. My buddy reloads and makes me my bear rounds. 320 grain hard cast lead at the maximum pressure safety will allow. More than likely you will never be charged. I see bears on a weekly basis and they are always running away from me when I finally do see them. They want nothing to do with humans. That being said, when venturing into bear country you need to be prepared to protect yourself and your family.