You're missing the point. They move too fast, often in thick brush and partially obscured to count on hitting them in the head. What's more, a brown bear's skull is angled and muscled in such a way that in a head on presentation deflection can easily occur, especially with a projectile as ballistically inefficient as buckshot. I would take pepper spray over a shotgun with buckshot, and that's saying something.
Also, feeding bears and habituating them is a very bad idea and likely illegal. One or both parties will end up in trouble.
