Hi jack,
If you read the OP you will see that I had pretty much the same opinion as yourself right now.
I'll try to explain what I'm seeing now but I also spent a bit of time reading Pat Speer's work regarding the history of headshots and how it relates to JFK. It was quite illuminating and helped me understand the discrepancy I was seeing in the Z-film regarding how JFK's scalp was hanging forward in the Z-film (something you seem not to have noticed).
I already know your position and I'll repeat that you can't base any conclusions on how JFK's scalp was hanging, especially if a frangible bullet was used, which it was.
The first point is to clear up this notion of a bullet exploding in JFK's head. You mention it a couple of times in your post and I don't know where you're getting that information from. I can't find anyone who says the bullet explodes in his head.
Are you a newbie? Dr. Cyril H. Wecht has contended for decades that a frangible bullet exploded in JFK's head.
How can the magic bullet smash thru 3 bones and cause 7 wounds with no blow outs and show up pristine on the wrong stretcher with no DNA on it and the headshot bullet causes 3 massive blowouts and disintegrates in JFK's head? What kind of ballistics accounts for that without an explosion being involved? You should be able to answer with some simple physics.
As for JFK's head movement - even though I explained my current view in the post you responded to (which you don't seem to have picked up on) I would like to look into it further. I would like to ask you a serious question - If you study the Gif I posted (Reply #56)
of the moment of the headshot, what is the very first movement of JFK's head immediately after the impact?
Since Charles Nicoletti's shot from the overpass was a fraction of a second before James Files' shot from the knoll, JFK's head recoiled backward until Files' frangible bullet exploded in JFK's head forcing it to the left and blowing out JFK's right temple. The explosion also blew out the top of the skull where Nicoletti's shot entered and exited thru the occipital region in the back of the skull. This is based on the trajectory of Nicoletti's shot from the overpass:
You can see the explosion as the frangible bullet blows out JFK's right temple:
One last thing, you're idea that the Z-film has been altered to cover up a blow out in JFK's head is 
The Z-film has not been altered.
To any observer of the moment of the assassination, the most obvious giveaway that there is a shot from somewhere other than the TSBD is the 'back and to the left' movement of JFK. If that can't be altered there's no point in altering anything else.
How could you possibly know that the Z film has not been altered? Because it has. The FBI returned a COPY of the Z film to Zapruder, which had sections spliced out, which Zapruder could not account for. The FBI claims someone damaged the film and spliced it back together. Sure.
If this was a conspiracy, then the FBI scrubbed the film for any evidence that countered the LN narrative. That would include anything that happened as the limo rounded the turn onto Elm St. and nearly stopped directly in front of the TSBD to avoid curbing out. Why didn't Oswald take the shot then? JFK was stopped only 60 feet in front of him. Why did he wait so long before taking the 1st shot? At any rate, the FBI felt the need to remove that section of the film before making a copy of it.
Other possible edits include removing any signs of a shot from the front, such as the blow out at the back of JFK's head. That one is easy-peasy. Just black out the back of the head on the original Z film on a few frames such as 323, before you make a copy:
One last edit might have been to decimate some frames to speed up the limo at the Turkey Shoot point, where it slowed down to a near stop so Hill could climb aboard. You can easily do that with an optical printer when you are making copies. You wouldn't need to skip very many frames to speed it up just enough to avoid a complete stop. You wouldn't even notice the discrepancy between the Z and Nix films but it is easy enough to do that for all the films. Was anyone returned an original negative? If the FBI gave up the original negatives, we would know. So where are they?
But the real question you should be asking yourself is why the limo slowed down at all. Where in the SS training manual does it say when you are driving the POTUS around and you hear gunshots you should slow down, especially at the Turkey Shoot Point? Then apparently you are supposed to turn around and watch the POTUS' head explode before stepping on the gas and getting outta Dodge.
Face it, this was a conspiracy and the FBI were the cleaners. Their job was to scrub all evidence of anything that contradicted the LN narrative. That included confiscating all photos and films at the scene, and any forensic evidence and testimony from witnesses. Hoover's orders.
