Build your own off of a Mega, Noveske GenII, Aero P., POF, Spikes, BCM, DD or ?? big name you want. From there add a POF, KAC or PWS receiver extension (research em and you'll understand why), Springco Blue spring, H2/ST-T2 type buffer. Add KNS Pins and a POF/WC TTU/LWRC? or tuned trigger...