Abstract: A see-through periscope for sighting-in optical sights or open sights by co-aligning one type of sighting system with the other type. The small see-through periscope is preferably used with firearms that have two conditions: (1) the rifle must be equipped with open sights, and (2) a gap must exist between the front of the optical sight and the rear open sight where the periscope can be mounted. Four unique mounts allow the periscope to be used with both magnifying or non-magnifying optical sights of different types, sizes, and shapes and open sights of different heights. The mounts position the bottom mirror at the height of the open sights and the top mirror at a point higher than the optical sight. The bottom mirror captures an image of the open sights aimed at a target and reflects that image to the top mirror, which in turn reflects the image across the top of the optical sight and into the eye of the shooter.

Abstract: A see-through periscope for sighting-in optical sights or open sights by co-aligning one type of sighting system with the other type. The small see-through periscope is preferably used with firearms that have two conditions: (1) the rifle must be equipped with open sights, and (2) a gap must exist between the front of the optical sight and the rear open sight where the periscope can be mounted. Four unique mounts allow the periscope to be used with both magnifying or non-magnifying optical sights of different types, sizes, and shapes and open sights of different heights. The mounts position the bottom mirror at the height of the open sights and the top mirror at a point higher than the optical sight. The bottom mirror captures an image of the open sights aimed at a target and reflects that image to the top mirror, which in turn reflects the image across the top of the optical sight and into the eye of the shooter.