When training bird hunters, McDaniel would move the student up to a .22 rifle without sights. He would throw the same range of aerial targets, from silver-dollar size to empty .22 short cartridge-cases. The student could not directly perceive the flight of the .22 bullet, but by then his subconscious had learned how to judge parallax and trajectories and time-to-target, and it would experiment on its own to nail down quickly the differences between a fired BB and a fired .22-short bullet, and swiftly get on target.