A co-worker had a mounted black bear's skull in his office (he also has a mounted gnu's head) and it didn't impress me as being any thicker than a human's and, besides, we all know some thick headed people. It was smaller, however, and the odds of hitting one in the right place becomes positively prolematic. Which leads to a question.
Where is the right place and when do you start shooting? At least one thing I read ages ago supposedly written by someone with African experience implied near contact distance, which sounds uncomfortably close. But on the other hand, if you start shoot when the bear or other target is far enough to give you time or the need to reload doesn't sound like a good idea either. But here I'm assuming that the bear isn't going to jump you from a tree and that you will have a half-second to think it over. If the problem is a lion, very rare in the east, the circumstances are a little different.
I've seen four bears in the woods and, believe me, even a cub on its hind legs looks pretty big to me. They make all the deer I've seen look pretty small. Also, I'd say that if you were to shoot at a bear and thought you needed to, you would hardly notice the recoil or the noise.
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
Buy War Bonds.