At no point have I ever tried to argue anything from JFK's facial expressions.
The resolution of the Z-film is clearly not good enough.
Never have I even hinted at using this aspect of the Z-film to determine reactions.
On the contrary - it is you who keeps dragging in JFK's facial expressions as if can you discern something from them. Does this quote ring a bell:
"We cannot see JFK's face until z225 and in that frame it is already contorted with an unnatural expression."
I have pointed out the resolution is not good enough to reach any conclusions using facial reactions but apparently you can reach conclusions from it.
Really?
In order to prove that the reaction beginning at z226-227 is the first reaction to being shot at z223, you have to demonstrate that he was NOT reacting before then. By suggesting that the reaction began at z226 and not before, you are saying that he is not reacting in z225. So you must be confident about that. I'm not.
But, of course, that is not all one must establish in order to prove that the bullet struck at z223. One must have evidence that the reaction beginning at z226-227 is the physical reaction that a person suffering the injury that JFK suffered would have to exhibit within 165ms to 220 ms. after being hit. I have yet to see that kind of evidence. That is what Lattimer was saying with his Thorburn argument. You are not making the same kind of argument.
Can you explain this quote from one of your previous posts:
"No nerves were severed in JFK's neck and C6 is well below the bullet path. "
In one moment you're saying the bullet enters JFK's back above the C6 vertebra then your saying the bullet path is below C6 (below the brachial plexus.
It is clear you are willing to say whatever it takes to "win a point".
I made a correction in my subsequent post, which you must have read because you quoted it. I said:
"Sorry. I should have said that the bullet path was below the C6 vertebra. The bullet entered the upper back below the cervical (neck) part of the spine. The autopsy report (Warren Report, Appendix 9, p. 6):
"The other missile entered the right superior
posterior thorax above the scapula and traversed the soft tissues of the supra-scapular
and the supra-clavicular portions of the base of the right, side of the neck.
This missile produced contusions of the right apical parietal pleura and of the apical
portion of the right upper lobe of the lung. The missile contused the strap muscles
of the right side of the neck, damaged the trachea and made its exit through the
anterior surface of the neck. As far as can be ascertained this missile struck no
bony structures in its path through the body.""
Constantly introducing 
straw man arguments, twisting and misrepresenting what is being said.
Anyone can look over the last few pages and see the contribution I am making and your own contribution.
Your model has failed - passing under the oak tree at the time of your proposed first shot, the impossible ballistics of your proposed second shot and now this - a delay of over a second and a half between being shot and the multiple extreme, rapid and co-ordinated reactions of both JFK and JBC. The speed of these physical reactions is startling, measured in milliseconds. To suggest they come after one and a half seconds is preposterous. One and a half seconds may not seem a long time but it is an eternity when dealing with such rapid reactions.
First of all, I thought we were talking about JFK's reaction after he emerges from behind the sign and whether that was unequivocal evidence of a shot at z223. What does the tree have to do with that?
Second, there is only a delay of a second and a half if he is not reacting at all when we can't see him. There is only a "co-ordinated reaction of both JFK and JBC if JFK is NOT REACTING when he is not visible prior to z225.
Third, your analysis assumes that JBC is reacting to being hit in the back on the first shot. That is not what he said occurred. He said that his reaction to the first shot was to turn around to see JFK. That was what Nellie said as well. So did the Newmans who were standing right there 20 feet away. That is what the police outriders said he did as well. That is what the evidence says was JBC's reaction to the first shot. So even by your own theory that the first shot was at z223, JBC's reaction beginning at z228 or so is to start turning around to see JFK. And that is exactly what he proceeds to do at that point.
There is no sane proposal you can make that accounts for this time gap.
Weak attempts at muddying the water - maybe there was some kind of subtle reaction we can't see before z225 - cannot explain the sudden, co-ordinated rapidity of these physical reactions.
Again, they are co-ordinated only if JFK is not reacting before z226-227.
The time gap for JBC's reaction is due to the fact, as he testified, that he was not hit in the back on the first shot so his reaction was due to the time required for his brain to process that he had just heard a rifle shot, that an assassination attempt was underway and feel concern for the President and then to start turning around to see him.
JFK's reaction was to having a bullet pass through his upper back and neck. Since it did not strike bone, the reaction could have been a fairly immediate but gradual reaction such as facial expression and hand movement followed by the more demonstrative reaction beginning at z226 when he realized he could not breathe.
