Black Bear and the various deer in my state vary a lot in size. That, and while I find bear generally easy to kill, they get tougher if they get riled up.
While I used a .243 for a while, I came to feel more comfortable with a 6.5x55 in a '94 Carbine. A 140 grain sp at low velocity penetrates and kills very well.
I now have a Kimber Hunter in 6.5C I may start using too.
