Between the First and Second Shots
1. Oswald pre-selected the south curb of Main Street to zero the scope. He had no other choice.
2. Aim, fire and note where dust kicked up relative to the crosshairs. <Clock starts. 1 sec.>
3. Adjust windage and elevation screws. <4 sec. max.>
4. Operate bolt. <2 sec. max.>
5. Wait for JFK to appear from behind oak tree. <as needed>
6. Acquire target and fire. <up to 2.5 sec. Clock stops.>
Total 9.5 seconds between the first and second shots.
Exactly where the FBI spliced 7 frames from the Tina Towner film to hide her jiggle reaction to that very early first shot.
You don’t just pick up a rifle and start shooting!
Details in The Final Truth, pp. 122‒123. http://www.thefinaltruth.net
17 experts and gun manufacturers weigh in on the need to zero a reassembled rifle: http://thefinaltruthjfk.blogspot.com/2015/02/for-those-who-might-like-bit.html.