Developed and patented by James M. Leatherwood, the Adjustable Ranging Telescope (ART) system combines a rangefinding scale inside the telescopic sight (scope) with an adjustable cam built into the scope's mount that raises or lowers the rear of the sight to compensate for the trajectory of the bullet. The cam is preset for a specific cartridge; i.e. the 7.62 mm NATO round. In use, the shooter first adjusts the magnification of the scope such that the ranging brackets subtend the target. Since the range cam is locked to the magnification ring, the range is automatically set and the drop of the shot is accounted for. This then allows the shooter to place the scope's aiming point directly on the target without having to hold over or under to compensate for the bullet's rise and fall.