I was talking more about preserving your life, not going in planning on hitting it with an arrow AND a gun. Hope for the best, but prepare for the worst. When Tred Barta took a grizzly with a long bow and home made wooden arrows, he had a guide with a large caliber rifle there to back him up. He didn't need it, but he had it available.

I wouldn't suggest that you use a bison as your first animal with a bow, but if you do, remember aim small, so you miss small.