Abstract: A tank gun sighting system in which there is a visual sight having a boresight mark permanently aligned with the gun and in which an electronic aiming mark is superimposed on the visual target scene. The aiming mark is controllable by the gunner with effectively zero inertia and can be laid on the target very quickly. The gun control equipment is directed by a signal which is the difference between the aiming mark off-boresight signal and the gun movement signal derived from a rate gyro in the gun control loop. The aiming mark is thus stabilized on the target scene, and in particular on the target, as the gun slews round to reduce the boresight/aiming mark error.An aim-off signal is calculated and added in to the gun control to lay the gun at the required angle off the aiming mark.