My experience with elk and black bears leads me to think that anyone hoping to stop an aggressive brown bear with any conventional handgun is indulging in delerious, delusional, wishful thinking. Sure, a handgun is better that an axe, or flashlight, or canoe paddle, but not by much. I even question the efficacy of 12 ga. slugs --- lots of delivered energy, to be sure, but doubtful penetration (I think they're "recommended", i.e., "suggested" because shotguns are inexpensive, not because they're especially effective...) I wouldn't want to be more than arms length from a potent rifle in brown bear country, where and when conflicts are predictable. Note what Iggy said about the limitations of 10mm pistol ammo to take down cattle --- a far cry from an aggressive bear.