Lots of variables...like the size of the bear and how close you are and what type rounds are you carrying...In simple terms, it is not the BEST round for the job, but a well placed round to the heart would work..especially the scrawny brown bears here in Kalifornia...I would be more concerned if it was a Kodiak or a Grizzly in which case a .44 magnum would be my first choice for handgun, or better yet, a .308 rifle at 300 yards, lol. Still, multiple, well placed rounds with a .45 should work.