Come on now John. We do Not know that ALL of those guys were shot in the head. What I do know is that NOT a single head EXPLODES. Not 1!

What I do know is that NOT a single head EXPLODES. Not 1!
Kennedy's head doesn't literally EXPLODE either, so what's your point?
We do Not know that ALL of those guys were shot in the head.
Well, the guy at the front certainly was shot in the head and there is an expulsion of a cloud of biological matter just behind the hat flying off. There is simply not enough "Zapruder" type resolution to make out the rest.

And considering that we know that the first Soldier was struck in the head and nearly all the shooters are aiming at the same height it follows that their targets were the Soldier's heads. The idea was to kill them, not give them survivable flesh wounds. Doh!

But at the end of the day wherever you think they may have been struck, your absurd theory that the force of a bullet flung Kennedy into the back of his seat has been thoroughly destroyed.
JohnM