Gun Deflection

Gun Deflection (or Scale in American parlance) is the angular difference between a gun's orientation in bearing and the line of sight to the target. This offset is intended to place the shell on target after factors that cause lateral deviation of shell or target during time-of-flight have played their role.

In riflery, this is often termed "Kentucky windage,", but in naval gunnery it takes on an even larger dimension owing to greater times-of-flight, speeds of firing vessel and target, ballistic drift and even Coriolis effect.