Ok, I watched your vid. Hope you checked out mine of the roof.
I'm staying with my initial finding. He was hit from the front. And I think it might help you see why, if you look at or remember when JFK was (1st shot) through his neck and how he reacted. Kirk's shot would have caused something close to the same, had it been from behind. Instead, in the video from straight on, his head and arms don't move until after his shirt rises all the way up.
Then too, if it were an exit wound with that much of a wound blowing out instead of going in (ricocheted and round was tumbling)- There would have been a massive amount on his shirt, instead of the tiny dark spot we can see.