Debate has raged for fifty years over the three shots that killed President Kennedy.  But no one realizes that you don’t just pick up a rifle and start shooting.  First, you must always zero, or sight-in, your firearm as anyone with competitive rifle experience will tell you.  The first shot missed because Oswald used it to zero his Mannlicher-Carcano, aiming at the south curb of Main Street and causing the fresh bullet mark.  Privately and from the very beginning, the FBI knew the true cause of this curb gouge and they destroyed evidence and lied to the Warren Commission to cover up an early first shot.

The Final Truth: Solving the Mystery of the JFK Assassination, pp. 121‒131, 187‒195.
 http://www.amazon.com/gp/product/1490350578