You said "defensive use" and for me, that means penetration to break bones like shoulders or through bone to reach the cns. Lung shots, blood trails, dont really matter in a defensive situation, it will all be over by then. While I carry a 10mm or heavy loaded 45 Colt, my wife carries a .357 with 180 grain Cast Performance hard cast fn, over a stiff load of w296. I have no doubt the .357 will do the job on black bear.
While rare, black bear attacks do happen. A fellow across the canyon was hunting with his uncle, the uncle using a rifle wounded a good size bear (for Idaho) about 3 years ago. The bear turned on him and did a pretty good job of chewing on an arm and leg, severely injuring him. The guy pulled his handgun and killed the bear...he used a .357.
https://www.kivitv.com/news/boise-hunter-recovering-from-bear-encounter
