A sight base is configured to receive and secure a sighting device and is coupled to a base by a pin running in each of the grooves and rotatable about the pins between an aligned position with the base extending between the parallel walls and the optical device aligned with the sighting axis, and a deployed position rotated away from the aligned position. A detent releasably retains the sight base in the aligned position. A clamp member is carried on the lower extent of the base, and releasably engages the rail with selectively movable to tighten and secure the clamp and base to the rail. A lever is coupled to the base and to the clamp member, and has a camming surface configured to move the movable portion of the clamp into and out of engagement with the rail in response to actuation of the lever. The camming surface of the lever bears on a resilient surface carried by the base.