I believe that Willis was more than capable of determining that what he heard was a rifle shot. The first shot occurred after Croft #18 and after Betzner #3.
If we follow Willis' words":
"Mrs. Kennedy was likewise smiling and facing more to my side of the street." | | "When the first shot was fired, her head seemed to just snap in that direction ... she turned to the right toward him" |
Above: Three frames showing when Mrs. Kennedy began her rightward head turn, the head turn described by Willis as a reaction to hearing the first shot.
It's been said that Croft took his z161 photo long enough before the first shot that he had time to roll his film and snap another (that did not turn out). As the photo that did not turn out was said to have been simultaneous with the shots that killed the President, Croft's post-Z161 photo (the one that didn't turn out) was supposedly taken at the moment of the head shot.
However, I don't believe we have Croft stating those things verbatim. They're characterized that way in a FBI AirTel, which is hearsay and possibly misconstrued. It could be his Z161 photo was taken nearly simultaneously with one of the shots.
Croft Photo (Z162) | | Willis 05 Photo (Z202) | | Approximate size of Kennedy limousine relative to Willis photo, if Croft had taken a photo Z313 |
Croft stepping out in the street (for a better sight-line) or remaining where he was to take a photo in which the limousine was barely visible seems farfetched.
Betzner said he was looking down to wind his camera when he heard the first of two shots he later recalled, the latter one being the head shot based on what Betzner said about it. So the winding-the-camera shot he heard could be the shot heard before the head shot. In a three-shot scenario, Betzner has lost track of one of those shots.
As Betzner goes out of the Zapruder film in Z207, he is still lowering his camera and is not looking down. Assuming he winds his camera shortly thereafter, it could be an argument that the shot he heard while winding the camera was the proposed SBT shot at Z223.
The first shot could have occurred before Croft, Betzner and Willis05. I would think that most LNers believe it was a missed shot.