When I say it takes courage to change firmly held beliefs in the face of evidence that refutes those beliefs, that wasn't anything to do with an ad hominem argument. It's the truth. But it doesn't matter.
I wouldn't say it takes courage. I know you honestly believe that the third shot was after z313. It just requires examining the evidence and keeping an open mind. The problem with your approach is that by using a lot of
ad hominem attacks, as you and Jerry tend to do, the tendency is for you to tune out the other side because of who is making the argument rather than seriously considering the arguments based on evidence.
The problems that I have with the evidence are not because you and Jerry are making the arguments. It is because they do not fit the fundamental facts. They are built on speculation and discarding vast amounts of consistent and independent evidence. In the end, they really do not make sense either, but that is a relatively minor point.
The fundamental facts for which there is abundant cogent evidence are:
1. the shot pattern was 1........2....3 with the last two shots perceptibly closer together, in "rapid succession".
2. there were 3 shots.
We all agree on point 2.
Point 1. tells us that JFK was hit on the first shot. This is well supported by the evidence as you have pointed out.
These two fundamental facts do not establish that there was a shot around z270. That is established in two ways:
a) JBC being wounded on the second shot or
b) the headshot being the last shot.
There is strong evidence for a) and really no evidence that he was hit on any other shot. There is also strong evidence for b) but some evidence that may suggest it is not correct.
Regarding the evidence that the last shot was the head shot: Everyone in the president's car and in the QM including Clint Hill who was between the cars said that the headshot was the last shot. (Clint Hill did not recall a second shot but he accepts from what others in the QM told him that there was a shot while he was running toward the car before the one that he saw hit the president. This is set out in Gerald Blaines book "The Kennedy Detail").
I accept, based on all the evidence, that the head shot was the last shot not only because of this evidence but also because of the evidence that JBC was hit in the back on the second shot. There is consistent evidence that the second shot struck JBC in the back (from Powers, JBC, Nellie, Newman, Hickey, Greer etc) and no evidence that it did not. This necessarily means the headshot was the last.
So this leads inescapably to the conclusion that there was a shot just before the headshot.
In trying to pinpoint when the shot occurred I noticed a number of anomalous little details in the zfilm. Maybe I am wrong. Maybe the second shot occurred at z268 or z273 but I do not think so for many reasons which I have given. I believe the evidence indicates that the shot - which other evidence says must have occurred around 2 seconds before the head shot - occurred between z271 and z272. I am not persuaded of that because of those anomalous details seen in the zfilm. I am persuaded because of the fundamental facts and the third shot being the last shot.
So, I am not going to be persuaded by some argument based on interpretation of the zfilm around z270. I am only going to be persuaded by evidence that the third shot was after z313 and missed that is so strong that it outweighs the clear and consistent evidence that we do have that the headshot was the last shot. So, you see, it has nothing to do with courage.