GunTech,
I too live in bear country. In fact, my wife had an encounter with one the day before yesterday about 100 yards from our house. She carries a handgun when she walks the dogs, but in this case, she used one of those airhorns that uses a small can of compressed air. The bear took off into the woods when she "tooted", as she put it. We've had a couple of encounters with bears that have lost their fear of humans. Those are a different animal all together. The one time all I had was a S&W Model 59. As the bear got more obnoxious, that 9mm got smaller in my hand....
I've seen bears killed with a 9mm. In fact, one of them was with the very Model 59 I was carrying that day, loaded with old Black Talon loads. The bear went about 100 yards before it died, but it did die.
I carry my 10mm Witness when I walk the woods behind our house these days. I figure 16 rounds of 10mm 200 grain bullets will at least change ol' brer bruin's mind for him.
My real concern anymore is the increase in the cougar population around here. Since the liberals voted in the ban on baiting and hounds, both the bear and cougar populations have exploded, and the deer population has dwindled. Gee, who would have thought??
Anyway, back on point. For bears in the 300 to 400 pound range, I would (and do) carry a solid 200 grain bullet. You'll want deep penetration. I wouldn't consider a hollowpoint bullet for bears, since it won't drive deep enough to get to vital organs. Anything in the 1,200 fps range is what you're looking for. As you're probably aware, you need to get through that thick hair and hide, and once you do, break bones and punch holes in the organs.
I have a feeling you're getting a lot of advice from people who don't live in bear country, but have heard "stories". I've lived in bear country for over 40 years. Most bears will run from you, but once in awhile you'll run across one that didn't read the bear book of etiquette, or had been fed by some rotten do gooder, who thinks they're doing the bears a favor by providing free meals for them.
I'll be the first to admit that the 10mm isn't the ultimate gun for bears, but we're not talking about hunting them on a regular basis, just protecting our behinds, "just in case". I sometimes carry my 6 1/2" Model 57, especially if the bears have been really active around the neighborhood, but the 10mm is the one I carry the most when out and about.
Hope this helps.
Fred