Yes, dad taught us that a shot gun wouldn't defend against a bear. He said if we were ever in that situation to aim for the face, eyes and nose and hope to blind it and give you a chance to run.

But with a bear as powerful as polar bear, chances are still high that that won't work.

A 303 rifle shot in the mud is like an explosion, it's very dramatic, loud and visual. It does scare a bear.

A shotgun blast in the mud is not as dramatic, unless you fire it about 20 feet away from you .... which is too close to you and the bear.