Z-313 head shot, heard by many earwitnesses, as a shot about 1 sec after a previous shot fired. It was a rather remarkable shot that took account of JFK head turned about 45 degrees leftward, relative to his limo, leaning leftward and rather close to Jackie Kennedy, and adjustment for limo slowing from 15mph to almost a stop in only about 2 seconds,and with a vector force of cross wind gust up to 20 mph.