Alignment aid for gun muzzle reference system

Claim 1

An alignment aid for use with a muzzle reference system for a mounted gun having a telescopic gun sight: the muzzle reference system being of a known type including an indicator mark located on the gun mounting in fixed operative relationship with the gun sight and a reflector adjustably mounted upon the gun muzzle for reflecting an image of the indicator mark back into the gunsight, which gunsight is provided with an object lens, a graticule having a reference mark, an eye piece lens, a primary exit pupil from which the graticule is viewed, and an auxiliary optical system for focusing the image of the indicator mark onto the graticule having an auxiliary exit pupil located within the primary exit pupil; alignment of the system being achieved by setting said reflector to a disposition providing coincidence between said image and said reference mark: wherein the alignment aid comprises a viewing screen superimposable upon said indicator mark so as to confront said reflector, and a light source attachable to said gunsight so as to be located at said auxiliary exit pupil thereby to cause a focused image of said reference mark to be projected onto said viewing screen via said gun sight and said reflector.