Abstract: A mounting system securing a firearm sight to a firearm accessory rail includes a clamp with a downwardly open rail cavity for slidably engaging the rail. The sight is matched to a plate with pins that correspond to the sockets on the bottom of the sight, and the plate has sockets that correspond to pins on a base that contacts the rail. The clamp extends through the base and plate allowing the sight to be secured to the clamp. Securing the sigh to the clamp compresses the base, plate, and sight toward the rail, placing the system in tension to hold the sight to the firearm.