It was originally a lm4 cqb first gen but upper reciever was replaced to fix the first gen splitting problem. Parts list: DD mk18 rail 10.5 outer barrel Stock inner barrel but have a cqb km head inner barrel that will go with the rifle Maple leaf steel hop up chamber Maple leaf 70 degree bucking Magpul B.A.D. lever Ra Tech npas bcg Original bolt with danger werks flute valve will be included 3 pts epm mags 1 original stag mag Magpul afg replica I'm sure I'm forgetting something but will send shooting video on request and more pictures price is 300 but may be willing to negotiate