Friends I know have hunted Black Bear with roundball and killed them. Its all a matter of shot placement. I think that No Excuse would do just fine. Even with 80 grains of powder. Plenty juice to enter, hit vital organs, expand, and possibly even exit. All though fall bear have a lot of fat, and that can slow a bullet way down.
When I hunted black bear I was armed with a .54 caliber Renegade and roundball. I was in a ground blind. And had a sow and two cubs with in 10 yards of me. I admit I was a little nervous. But I was also sure that the roundball would have done the job at close range. I never did see a shooting bear. Saw sows, and small ones that I let go. But it was a fun experience. I really think that conical would do a number on a bear.