An adjustable accessory mounting clamp for mounting an accessory to an accessory rail, including a primary locking arm; a secondary locking arm; a threaded adjustment rod that is anchored, at a first end, to the primary locking arm, extends through an aperture in the secondary locking arm, and is threadedly coupled to a cam lever pin of a cam lever, wherein the cam lever includes at least one caming surface, such that when the cam lever is in a closed position, the caming surface contacts an outer surface portion of the secondary locking arm to provide tension to the threaded adjustment rod; such that a distance between the primary locking claw and the secondary locking claw is adjusted to accommodate varying width accessory mounting rails.