The sudden movement of JBC that begins at z271-272 and continues through z278 before he falls back.
The position of JBC at 271-272 relative to the sniper’s nest window is not compatible with a bullet entering and exiting JBC’s back and chest respectively in the places that it actually did enter and exit.
The bullet did not pass through the pleural lining of the chest. It went around the fifth rib until the last 10 cm, which it shattered, driving bone shards through the pleural lining and into the right lung. If you draw a path along the fifth rib from the very exposed right armpit that was facing the SN to just below the right nipple, it is almost a straight line - just a small deflection to the left. That deflection is consistent with the impact felt by JBC and with the force required to break the fifth rib close to the spine.
The bullet then exited the chest and struck the back of the radius well above the wrist joint in the middle of the french cuff, which happens to be pressed against the chest with the entry point on the cuff at the same point as the exit point (through the right jacket pocket).
In striking the back of the radius that is pronated so the back of the forearm is against the chest, the bullet fragmented and drove bone shards down into the wrist and made a jagged tear in the cuff. The bullet fragmented, as evidenced by the jagged cuff mark and the lead deposits as well as the large entry wound on the forearm.
Some fragments likely deflected up away from the point of contact and some possibly continued forward through the wrist striking the windshield. A fragment from the second shot struck the curb near Tague. That is consistent with several fragments, one of which went just over the windshield toward Tague and two of which did the damage to the windshield frame and glass. SA Greer (whose right ear was about 12 inches away) described a "concussion" from the second shot. That's not all, there is a change in the appearance of the wrist and hat which is consistent with a slight change in the position of the hat in the hand.
He does turn toward his left from that far right turn as he falls back on Nellie. He told the WC he intended to turn to the left when he was hit but wasn't sure how far around he was when hit. Nellie told DR. Shires that he was turned right when he was hit and did not mention turning forward or to the left before he was hit:
6 H 108:Dr. SHIRES.
She had thought, and I think correctly so, that he had turned
to his right after he heard the first shot, apparently, to see what had happened
to the President, and he then later confirmed this, that he heard the first shot,
turned to his right, and then was hit.I forgot about that a moment ago, incidentally. He definitely remembers
turning after hearing the first shot, before he was struck with a bullet. I forgot
about that.
Mr. SPECTER. When did Governor Connally tell you that?
Dr. SHIRES Oh, several days later.
Mr. SPECTER. While he was in the hospital?
Dr. SHIRES. Oh, yes. 4 or 5 days later and we were constructing the events.
....
Connally was in the room too, and reconstructing events, she related the story
of her last conversation with the President, relating to him, that the reception
had been warm and that she was glad he couldn’t say that people of Texas
and in Dallas didn’t like him and admire him, and she was very pleased with
the way things had gone the whole visit.
Then, the next event that occurred
was that she remembers hearing a shot, he remembered hearing a shot-he
remembers turning to the right, he remembered being struck by a bullet, and
his next thought as he fell over toward his wife was “They’re going to kill all
of us,” and that’s the last really clear memory that he expressed to me until
he remembers vaguely being in the emergency room, but very little of that,
and then he remembers waking up in the recovery room several hours later.