When it comes to dealing with dangerous bears on the trail, there are two and a half schools of thought:
The first is that you should practice avoidance, and know how to back down from a bear without making it feel challenged.
The second is that you should pack a powerful, deeply penetrating handgun. .44 magnums are generally assumed, but I've seen videos of park rangers dropping grizzlies with (a full cylinder of) "mere" .357 rounds.
The point-five, and where I stand, is that in bear country I'm most definitely going to practice avoidance and know my proper bear safety procedures, but I'd rather have a powerful revolver in my hand while backing away than not.
Brigid agrees, but takes a controversial stand:
She argues convincingly that a .22 is plenty of gun for grizzly.