Discover Complete Lower Receivers for your AR-9 build from Aero Precision and Battle Arms Development at Arm or Ally. These fully assembled receivers come with all internal components, offering a hassle-free solution for your AR-9 assembly. Engineered for compatibility and reliability, they are ready to be paired with an upper receiver, providing seamless integration and optimal functionality. Elevate your AR-9 shooting experience with these pre-built lower receivers, ensuring reliable performance and customization.