Years ago I was watching a program on Polar Bears. One of the guys in the film was an Eskimo. He ventured out from his hut without a firearm and was caught by a full grown Polar Bear. As the bear was trying to get hold of the guy's head he remembered a thing that his grandfather had told him, specifically, a bear would not bite anything that was wider than his open mouth. As his grandfather had told him, he raised his forearm which was wider than the bear's open mouth and put it in front of his face, elbow down fist up. The bear was apparently confused by this and was turning his head side to side trying to fit this object into his mouth. While the bear was distracted, he kicked it with his leg. The bear jumped back and the Eskimo bolted for his cabin door. He closed the episode by saying that he had to get outside with his "Big Gun", a 30-30.

Anyone who's ever dressed a deer killed with a 30-30 knows the reality of what it can do. The carbine shot into the skull of a bear at close range kills it. Several well placed shots would definitely kill it. All 15 in the wrong places wouldn't kill it.