I think one would be hard pressed to find any other gunshot case where a group of people refuse to believe the person who actually experienced the shooting and who identified the moment of impact after carefully studying a high-quality print of the film of his shooting frame by frame and under high magnification.
Getting back to Connally's stiffening and frowning, which SBT believers implausibly interpret as a wound reaction, the HSCA's photographic experts determined that the stiffening and frowning actually starts at Z222 (6 HSCA 17), and I agree with them. This poses yet another unsolvable problem for a Z224 SBT hit, and also for a Z220-223 SBT hit. Since Connally begins to stiffen his shoulders and upper trunk and frown at Z222, this means the bullet could not have hit him any later than Z218, since it takes humans at least 4 frames (220 milliseconds) to physically react to "severe external stimulus."
Obviously, Connally stiffens and frowns starting in Z222 (if not before) because he has just heard a gunshot. Naturally, this would have caused him to tense up and frown. He explained that he turned to try to see JFK because he had heard a shot, and we see him starting to finish his rightward turn in Z222, when he reemerges from behind the freeway sign. So, yes, of course, he was worried about hearing a gunshot, and so he tensed up and frowned as a result.
Of course, Connally carefully studied all the frames after he reemerges from behind the freeway sign for any indication of wound reaction and bullet impact. He said he saw no indication before Z229 that he was hit, and he chose Z234 as the moment of impact. He said he was certain about this.
But, even if you want to reject the conclusion of the guy who actually experienced the wounding and who knew himself better than anyone else, you are still left with the fact that the reaction that starts at Z222 could not have been in response to a Z220-221 hit (and obviously not to a Z223-224 hit either).