I'd take the 300 WinMag for black bear, not so much for killing power as both rifles will have more than enough energy to get the job done. I'd prefer the WinMag for bear to get the largest thru and thru hole that I can make in the animal for tracking purposes if need be. With the long hair a bear does not bleed much as a deer, with a thru and thru hole you have two places where it will be bleeding from. I hunt black bear, but the shots are not long shots, I use either a 35 Whelen (Barnes 225gr TSX), .358 Winchester (Barnes 200gr TTSX)or a 45-70 (Barnes TSX FB hollow point). Just curious when you say "long range" what do you consider to be long range?