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.
The changes in JBC - his sudden right twist and start of his forward motion and the sudden change in appearance of his right wrist, hand and hat occur between z271 and z272. There is also forward movement of the left sunvisor above Greer’s head between the same two frames.
Everyone in Dealey Plaza heard the second shot. Not all were counting them.
The time interval between Mason's Z-273 and Z-313 is about 2.2 seconds.
Between z271-272 to z313 is a spacing of 2.24 to 2.95 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 who made statements about the length of the interval between the fatal head shot and the shot that proceeded it characterized said interval as being in the former "pretty quickly" category, and how many said it was in the latter "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.
Almost all of the ear witnesses described clearly spaced shots. As Zapruder described, there was tremendous reverberation that persisted for some time.