The deceleration of the car
Some say the forward movement of Kennedy's head is due to a deceleration of the car (some will even say the car stopped!).
Here is a limo animation (frames 311 to 313). You be the judge. I can see no noticeable movement but the violent movement of JFK and a slight movement of Connally.
Note that the apparent movement of the car (looks like it is rocking) is an illusion due to a camera movement.
Look carefully at agent Kellerman, the one seated in the right front seat. Some people focus on him and can see a forward movement. There was indeed a movement, only it happened AFTER the headshot.
Here is the demonstration of this in 2 animations:
Kellerman's movements (1) Kellerman's movements (2)
Back to the Headshot