Shot-2 was at Z218. The headshot was at Z312, ie 94 Z frames later, ie 5.14 sec later (based on 18.3 fps).
If the gap between shot-1 & shot-2 equaled the gap between shot-2 & Z312 then shot-1 was 94 frames earlier, ie at pseudo Z124 (ie 9 frames before Zapruder's sequence starts at Z133).
If the gap between shot-1 & shot-2 was 50% longer than the following gap then shot-1 was 141 frames earlier, ie at pseudo Z077.
If the gap between shot-1 & shot-2 was 100% longer than the following gap then shot-1 was 188 frames earlier, ie at pseudo Z030.
However, not one member in the history of this forum has acknowledged even one atom of this simple truth.
But many members here reckon that the gapage was BANG........................................... BANG...................BANG.
If u insist on shot-2 being 4 frames later than Z218, ie at Z222, then Z124 becomes Z128, & Z077 becomes Z083, & Z030 becomes Z038.
Holland's estimate for shot-1 was Z105 or Z107 or somesuch, & i agree with Holland.
Z105 is 113 frames before Z218, which is 20.2% larger than the final gap of 94 frames.
Z105 is 117 frames before Z222, which is 25.6% larger than the final gap of 90 frames (if u insist on shot2 being at Z222 instead of my Z218).
So, Holland has copped a lot of flack on this forum for suggesting that shot-1 was as early as Z105.
But, Z105 only needs gap-1 to be 20.2% larger than gap-2 (or 25.6% larger if u insist on shot-2 being at Z222).
If members are happy with their claims that gap-2 was significantly smaller than gap-1 then members should be happy with Holland's Z105.
Hence gap-1 was 6.17 sec, & gap-2 was 5.14 sec, total 10.31 sec.
The silly estimate of say Z169 for shot-1 means that gap-1 is 49 Z frames (& gap-2 is 94 Z frames), which is BANG........ BANG................... BANG. Stupid.
Hence silly gap-1 was 2.68 sec, & gap-2 was 5.14 sec, & the stupid total 7.82 sec.
The above are based on when the shots landed, not when fired, & not when heard.