A 243 will kill a bear but I don't think anyone would consider it an ideal bear rifle. Killing a bear while deer hunting is different than deliberately hunting bear. IMO if you're serious about bear hunting then a larger caliber is need. I strongly believe that when hunting bears a 308 cal rifle is minimum. Bear hunting with hounds or over bait gives you a close range shot. I would rather have a 30-30 or 35Rem than a 243. Spot and Stalk hunting requires something with a little more range, like a 308 or 30-06. I usually still hunt bears and sometimes hunt them behind hounds. When I do, I use a 338-06 or a 308. I'm not saying that a hundred other rounds won't kill bears but I know what I feel comfortable with.