[carlr]

Guess it would be better than nothing but you would need a clean head(brain)shot.This is not likely on a charging bear.
You need something that can stop the animal with a shot to its vitals and even that wont put it down on the spot.
I don`t have a handgun but to anyone in the know,would any handgun,not a Thompson or equivalent have the penetration necessary to dispatch a bear short of extremely close in the skull?

[Spktyr]

Not really. Any handgun is chancy against a bear, even the very largest caliber handguns.

After seeing what a bear can do to a person, I'll take a .45 (whatever you carry, you have to be able to HIT and SCORE on the bear for it to be worthwhile, and that means a semiauto for me) at a minimum. My preferred weapon for hiking or back country anti-bear armament is a 12ga pump or semi shotgun with magnum slugs.

[Richard-SIA]

According to an Alaskan native I know, who used to work as a guide, there is at least one case of a one shot kill of a grizzly using a .22!

The Eskimo lady got a lucky shot off, hit the bear in the brain through the roof of it's open mouth while it was charging her.

My personal favorite for a handgun would be an AMT Automag V in .50 AE, but they are hard to find.

There are some revolvers (HEAVY!) and derringers in 45-70.