Embodiments of the application can include an integrated rail system construction for a firearm with transverse ribs or tabs (e.g., picatinny rail) to include an undercut or slot at a front and/or rear face to cooperate with mounting structure for a detachable accessory. Embodiments of a rail structure can include a channel to pass wires used to power accessories mounted to the rail. Embodiments of the application can include methods for manufacturing an integral rail system.