The "Turkey Shoot Point" (Z313) was intended to disguise multiple shots if the Mauser didn't score a head shot before then. The umbrella man signaled the shooters, otherwise, simple geometry disproves the head shot came from the TSBD.
Below shows an overhead view of JFK's orientation at Z313 if a shot from behind blew out the right side of his head. According to this view Zapruder could not have filmed JFK's profile at the TSP, when clearly he did. LNers?
To be fair to you LNers, I have provided a solution 4 u.
This trajectory works for the head shot. So where in the autopsy photos did they show the entrance wound? Was it anywhere near the red circle?