The system is comprised of two machined aluminum level housings calibrated to their integrated levels. It is attached to the guns barrel while the smaller Reference Level is placed on scope base, bottom half of a ring or other flat surface perpendicular to the vertical axis of the gun. The gun is then rotated until the Reference Level is aligned. Its tuning adjustment knob on the Barrel Clamp Level is then turned until its level is centered to match the Reference Level. At this point the Barrel Clamp Level is calibrated to the guns axis. The Scope can be installed loosely and the Reference Level placed on top of the scopes turret cap. The scope is rotated until the Reference Level is aligned with the Barrel Clamp Level and then simply secured in place.