Five important factors were involved here. First, in shouldering the air rifle, the student would never bend his head so as to press his cheek against the gun-stock; instead, he would shoulder the gun in such a way that the gun-stock would be pressed against his cheek with his head still erect (i.e., he would move the gun to accommodate his head, not his head to accommodate the gun). Second, he would consistently shoulder the gun exactly the same way each time. Third, he would never hesitate before pulling the trigger but would pull it the instant the gun was seated against his shoulder and his cheek, making a controlled snap-shot. (If he delayed the shot and tried to track the washer and align his gun with his conscious mind, he could never become proficient at this type of shooting.) Fourth, the student never once looked at the gun barrel; instead, he stared at the flat washer until he pulled the trigger, and then he focused upon the flight of the BB he had shot to see where it would go in relation to the washer. And fifth, McDaniel would cock the BB gun for the student for each shot, so as to avoid tiring the student and spoiling his concentration. It was not enough for the student merely to perceive the flight of the aerial target; he had to focus and concentrate solely upon it for McDaniel's training program to work. If the student began tiring, McDaniel would declare a short rest period. The student had to concentrate his full attention on the target.