I do not know of anyone who has actually used a 10mm to stop a bear attack, but the .357 mag has been used many times on black as well as grizzly bears. The hotter 10 mm loads are at least as good as the hottest 357 mag loads and in my opinion are slightly better. The Glock is lighter and easier to carry than any revolver, is more accurate in rapid fire, and carries 15+1 or 17+1 rounds vs 5-6 in a revolver. 18 180 gr. Jacketed Hollow Point (1,350fps/M.E. 728 ft. lbs. from buffalo Bore) rounds in a row will bring a lot of heat to any bear. Even in a 50% miss situation I'd take 8 or 9 730 ft. pound rounds vs 2 or 3 for a big bore wheel gun.
I also think the Glock makes a better outdoors gun. Revolvers are dead reliable as long as they are kept clean. Drop your wheelgun in the mud while the bear is charging, and you'll likely be bear scat tomorrow.
There are bigger guns that bring more energy on target. But, for real world conditions I think the 10mm is a pretty good compromise of power, reliability, capacity and tote-ability, but to each his own. I guess if I knew for sure I'd run into a bear, I'd bring a rifle, but even in these bear infested mountains we only bump into a few each year. The best gun is always the one you have with you when you need it. Hell, when a bear comes around looking to maul and/or eat you, anything is better than throwing rocks.
I have a three step bear defense plan.
1) Wait until a reasonable range, and shoot until I'm out of ammo.
2) Switch to bear spray and wait until it's within 20 feet, and spray away.
3) Lie down and try to taste real bad.
'76 CJ-7, '43 CJ-2a, '78 Bronco,'78 CJ-7, '75 CJ-5, '78 CJ-7, '80 CJ-7, '78 SJ, '79 SJ, '78 and a '76 FJ-40 , '90 XJ, '91 XJ, '86 CJ-7, '95 ZJ, '68 CJ-101 Commando, '00 TJ, '68 M-715, 2 '86 Military Blazers, '96 LR Discovery, '86 CJ-7, '91 YJ, '99 TJ, 07' JKU Rubi, 1988 YJ, 1973 Commando, 3 Diesel Excursions....
Now back to a 2013 JKU Rubicon with "stuff", planning 37's with minimal lift.
I've tried them all... Jeeps are still the best. (0||||0)