Smith & Wesson MP15 Complete Lower Receiver 5.56x45mm NATO, Black Aluminum, Collapsible Stock Build your next AR with confidence using the Smith & Wesson M&P15 Complete Lower Receiver, precision-engineered to mil-spec standards for unmatched reliability and performance. Designed for 5.56x45mm NATO platforms, this complete lower includes a collapsible 6-position stock, factory-installed lower parts kit, and a forged aluminum receiver for rock-solid durability. Whether you’re completing a build or replacing an existing lower, the M&P15 lower provides a drop-in ready solution with the legendary quality of Smith & Wesson. Compatible with all mil-spec AR-15 upper receivers, this lower ensures a smooth