All kidding aside for a moment....I heard of this one Alaskan who used to carry a .44 Mag with him, got charged by a Brownie, got off five rounds before the bear finally dropped a couple of feet away. He allegedly stated that he was "saving the last round for himself." Now he never goes anywhere in the bush without a .338 Win Mag.
A .44 mag is starting to get into the realm of a "reasonable bear pistol."
We had a Kodiak Brown Bear walk through our camp one night. It stopped about 20 yards from camp and had a stare-down with us (luckily, our fish was in a cooler out in the middle of the river!).
One guy shot a .357 over its head to scare it away.
The bear sat down.
We then shot a .44 mag over its head, and that was enough to scare the bear off.
You hear stories of "miracle stops" all the time . . . I remember a story of a kid with a spear. A polar bear was charging him, so he stuck the spear in the ground, and dove out of the way. That stopped the bear.
I've even heard stories of people dropping charging bears with .40's.
It would be a cold day, however, before I relied on anything less than a shotgun to stop a charging bear.
But, the real lesson to learn is that if you aren't looking for bear, MAKE LOTS OF NOISE!
Not spooking a bear is the best way to stop a charge.