I used a revolver on a bear that came in on a Moose killed and it worked to perfection and only 2 shot required
Thanks for reminding us of that event, John. You are one of 6 people I've spoken to personally who killed charging bears with a handgun. Most recently, my good friend's son killed a grizzly as he and his client were field-dressing a Wyomin elk. He had a S&W 357 Magnum, which many people say isn't adequate for bear defense. In my view it certainly is adequate, as is a 9mm if Phil Shoemaker's example is taken into account.
A very good article was published a year or two ago that showed handguns are indeed highly effective as bear defense weapons. I'll see if I can locate it.