If by "bears" you mean black bears, the fear of them charging doesn't match the reality. They don't want anything to do with people. I bowhunt and turkey hunt in bear country. We run into them all the time and they're not a problem. If by "bears" you mean grizzlies, that's a whole different matter. As the saying goes, "You can kill 'em but you can't stop 'em". Having said that, given the choice between the two, I'd go with a 12 ga. shotgun. A 12 ga. slug has a lot of impact. Otherwise, bear spray has been shown to be very effective threat stopper.