A small black bear with the right JHP and good shooting....
might work OK.......DEFINATELY not for big bears!!!
Most time they leave you alone.
Suggest some Hornady or Winchester 230 gr plus p JHP's.
I have heard that if it is truely charging to aim for the shoulder and try to break it, without the structure to support the weight, the bear becomes immobile. The cranium is pretty thick and deflects bullets pretty good....From the side, if it is charging someone else, the base of the skull to break the neck. I have heard bears(the big ones anyway) can have their heart shot up and still rearrange your anatomy in a most unpleasant fashion.
In my younger years, I hiked and climbed all over the Cascades.....Washington and Oregon, and some rough northern California terrain as well. I carried a LW Commander with a mix of 215 gr LSWC reloads and the 200 gr Speer 'Flying Ashtray' in one of those GI cross chest rigs(good for backpacking!).
I saw six black bears, during that time...they all went the other way as soon as they realized I was there.
Now the fours years I spent in Alaska......the .45 auto was a might puny. So was the .44 magnum(back then, both are better now with loads available...but still not better than a shotgun with Brenneke slugs or a rifle...Marlin Guidegun 45-70 gets my nod of approval here. I'd probably get a .460 Rowland conversion barrel for my Government model(45 at 44 magnum velocities....
www.clarkcustomguns.com) if I was venturing out much in mountains now...just to have alittle more thump!
Dealing with bears you are better off armed with a rifle..but the blacks, from what my experience indicates, should be too much of a problem and I rather have a .45 auto I can control and reload quickly than some feisty magnum revolver I cannot!
A couple of pennies worth....
Jercamp45