Close friend of mine lost his wife to a bear attack up in Alaska, and he almost lost his own life. With a 44 he stopped a bear charging him, and the bear slid right up to his feet on the rocks where he was. By the time you are close enough to be sure to get a shot into the skull or the heart, you still have to get out of the way after shooting.
A good friend of mine stopped a charging grizzly with one shot from a 30-06. It slid to within 15 feet of him. He is British, though, and still thought that “gun control” was a good idea.