Do you know what is meant by “a reassembled rifle will never hold its zero”? Lee Oswald knew what it meant and it dictated his actions. Those actions caused the 1.........2....3 shot pattern.
The captain of my high school rifle team could routinely zero a rifle in one shot. He was on the scope. I would fire once from prone at the center rings of the A-17 type target. He would call out the adjustments (e.g., 2 up, 3 left). My second shot was almost always a bull.
That, my friends, is zeroing a rifle in one shot.
Lee Oswald, my friends, zeroed his reassembled rifle with the first shot.
That, my friends, is why the first shot ‘missed.’
It was aimed at, and struck, the south curb of Main Street.
You don’t just pick up a rifle and start shooting!