In Either scenario, a 3rd shot fired after Z313 is plausible.
Plausible - if it was not for the mountain of evidence that the head shot was the last shot: All occupants of the limo and Secret service car, Altgens, Gayle and Bill Newman, Zapruder.
2.3 seconds after z313 is z345. Clint Hill had reached the car by z345. One might wonder why anyone would try to shoot with JFK in this position:
Besides, it also makes no sense that the shooter would take another shot after seeing the results of the head shot.
