The .243 is adequate for deer, but I'd make out a will before I chucked a 100 gr. pill at a 4 or 500 lb. blackie. Oh, it'll kill him.....the only question is, before or after he tears you up. I'll stick with my .45-70 and 405 gr. Remingtons. In fact, they'll be out with me this evening after Mr. Bruin.
Pete