The question was a Bear comming at you. Now you are saying your 243 will run around and get behind the bear and shoot him behind the ear?.Now I see why nobody can get through to you.
Well, in that case I guess you would have to shoot it in the eye. When I was a kid, I once killed a rabbit with my pellet gun that way. It was an ugly death, but I remember telling everybody how good my pellet gun was on rabbits.
In the case of a grizzly, there might be one ugly death, and smokey with an eyepatch.
C. Davis