One only needs to look at Kennedy’s reaction and where the half of his head ended up for proof. You can’t duplicate that shot from the rear. I’ve tried many times with various objects (obviously not heads, but other things ranging from an old football to cantelope) and with several calibers of rifles, ranging from rimfire .22s to .308s.
I can do it easily from the angle suggested by the picket fence.
Oh, and saying “front” is misleading. Read my post on the Hill testimony. He said “right.” Given the angle of the car at the head shot impact, it is much closer to a right angle than to a “front” angle.
Kennedy’s head moves 2.3 inches to the front on impact. Zapruder’s film shows that. There is no damage to the left side of his head. Zapruder’s film shows that. There is no one at the corner of the fence. The Zapruder film shows that. All of the “red mist” erupts from a large exit wound at the front. Zapuder’s film shows that.
Oliver Stone’s movie “JFK” reversed the head shot for his movie so all of the injuries are to the back showing a frontal shot.
I have no idea who’s film you think you have been watching.
Study post 137. You might learn something about firearms.