Gerry Down has started a thread entitled "The physics of "back and to the left" in which he presents an argument that a bullet passing through JFK's head would not have caused much movement.
I would urge readers to look through this thread to get an idea of the massive forces that blew JFK's head apart sending pieces of skull flying in all directions. The idea that this massive force applied to JFK's head would have resulted in little movement of his head is utterly ludicrous.