Why don't we just cut to the chase and put the protractor away? Do you believe that: (1) Oswald was standing up when firing Shot #1, (2) Sat down, (3) reacquired the target, (4) worked the bolt action rifle, (5) Fired Shot #2, (6) worked the bolt action rifle, (7) Fired Shot #3 ALL in roughly 8 Total Seconds?
I doubt that Oswald used a support for his shot-1 at say pseudo Z103 to Z108, say Z105.
He would have been swinging the Carcano left to right while trying to get an accurate bead on the middle of jfk's back.
Thats why he hit the signal arm, koz he woz swinging, & shot a bit later than planned, & the signal & arm were never on his mind.
Then he probly used a support for his long range shot-2 at Z218, after jfk had emerged from the trees.
Z105 to Z218 is 113 Z frames, over 6 seconds.
Oswald would have seen that jfk wasnt hit by his shot-1, so Oswald needed a shot-2.
Then Oswald might have seen that his shot-2 had hit jfk, in any case Oswald stood up & back & he did not fire his last bullet.
Oswald would have seen Hickey shoot jfk in the head at Z313.