internals include new classic army m249 wire harness shs 13.1 gears zci balanced motor shs piston metal piston head ball bearing spring guide lonex oring air nozzle metal cylinder head madbull inner barrel i have a brand new hopup and micro switch in the mail to replace aswell just to ensure longevity of the m249 or to use as extra parts looking for an upgraded g36, ak, rpk, scar h, scar l, dsg gearbox or ssg gearbox with btc or titan. will look at others aswell