Looking forward to building a H&R M16A2 gray retro build. I have the M16A2 H&R gray stripped lower on the way from PSA. I am looking for an A2 stock (rifle length). PSA only shows an A1 (H&R) stock. Who sells an authentic representation of the USGI A2 stock with proper buffer tube, spring, spacer, buffer, and long screw for the M16A2 lower?