Outer barrel is metal, the rest nylon. Adds weight and is nowhere near as flimsy as the original plastic outer barrel. The nylon sight block is much better quality than the original. The tip is reverse threaded with a cap. Had to take it apart and install the battery wire connectors from the old outer as this one did not come with any sadly. The parts that makes the "charging handle" reciprocate is also a much better quality than the original, my last one was wearing out and had snapped in a place. Overall, even though the connectors needed adding, the quality far outweighs the trouble.