A couple of points I would like to make about the “explosion” of JFK’s head on the Z film being added or doctored; Mr and Mrs Connolly were splattered with brain matter and blood, and two, why would someone create an “explosion”, makes no sense.
Also a little on the last shot. It came from behind and was an explosive round, small diameter of little mass which does not cause something as heavy as a head to more when hit. Once inside what it hit it travels some distance and then explodes. The explosion exiting the front of the head causes the head to jerk backwards. I wasn't sure about this until I saw a video where they fired AR15 round into a watermelon and the watermelon had a small hole at entry and an explosion at the exit and the watermelon rolled backwards. Remember your physics, for every action there is an equal and opposite reaction.