JS-
I could never make heads or tails of any of the acoustics evidence.
I have looked at Z-film more times than I could ever want.
Gov. JBC is pushed forward ~Z-295, and JFK is shot Z-313.
Connally: I was knocked over, just doubled over by the force of the bullet. It went in my back and came out my chest about 2 inches below and the left of my right nipple. The force of the bullet drove my body over almost double and when I looked, immediately I could see I was just drenched with blood. (1 HSCA 42)
The above happens about ~Z-295.
In the Z-film, it sure looks like JFK's head is reacting to a shot from the GK. But who knows? Maybe there is a "carom effect" from a rear shot in combo with a back brace.
The "bang....bang-bang" cadence heard on 11.22 tends to rule out a lone gunsel armed with a single-shot-per-bolt-action rifle.
I have reasonable doubts LHO acted alone.