If you would look closely, you would see that JFK's hand was still moving down between Z224-225. His arms didn't start upward until Z226, just as JBC's injured right arm started upward.
A closeup of JFK's face in Z225 indicate he might have been exhibiting a facial expression in reaction to the shot, but his right arm was still moving down at that point.
The point is, Mason thinks (sic) JFK was wounded about 2.2 seconds earlier than Z-224 - Z-225, and that JBC was wounded about 2.6 seconds after Z-224 - Z-225.
LOL!
Secret Service Agent Paul Landis, who heard only the second (approx. Z-224) and third (Z-313) shots, correctly said there were "four or five" seconds between them.
Interestingly, he didn't hear Mason's mythological shot at Z-273.
Did anyone, really?
The time interval between Mason's Z-273 and Z-313 is about 2.2 seconds.
I personally would not describe a two-point-two-second time interval as "bang-bang," "clap-clap," "one-upon-the-other," or "immediately following," etc., but as, "pretty quickly," or "a second or two later," etc., etc.
Rhetorical question:
How many of the earwitnesses characterized the interval between the fatal head shot and the shot that proceeded it as being in the "pretty quickly" category, and how many said it was in the "bang-bang" one?
It seems to me that those who said "bang-bang" were fooled by the echoes in Dealey Plaza, and those who said "pretty quickly" (or words to that effect) were actually describing the approximately five seconds between Z-224(ish) and Z-313.