with the telescoped rifle considering the next two were "on the mark"?
Take a scenario with three shots fired from the Oswald window with the last being the head shot and second the SBT, and the intended target the center of the back of the head as it presented itself to the shooter. Then the second shot missed the head entirely and the last shot caught the head by half-an-inch.
For all anyone knows, the first shot "miss" could have been aimed at a front tire, or the driver's head. A few inches off to the side and the bullet goes into the pavement. Maybe the shooter didn't know that the limousine could still travel at speed with a flat.