Bluff - you were asking about a revolver. And I am going to stick by my guns (pun intended). A pistol with 10 or 15 round magazine is not going to do you any more good than a revolver in a charging bear scenerio. A bear coming at you from close range will not give you much time to unholster a handgun of any type and you would probably get one shot off at best. That is why I would recommend a big bored handgun like a 44 mag or 45 colt or bigger.
Heck, in the above situation, I would much prefer a 12 ga with slugs or buckshot.

And an even better option would be bear repellant spray. This is nasty stuff and the spray covers a lot of area.