Originally Posted by GabeGuitarded
I've completely disassembled mine, and when I had the upper receiver separate, it sounds like some form of metal (it pings when tapped with an allen wrench). I'm 99% sure it's metal. Keep in mind that may vary depending where you bought it from.
If you bought it from Shootsoft, Buy Airsoft, CAS or Velocity Arms, then the upper receiver is Nylon Fibre. Even says so on their websites. Like I said, the nylon fibre isn't cheap plastic. They are extremely tough and feel cold to the touch. I've gotten my hands on both G&Gs from Mach1/007 and Buy Airsoft/Shootsoft. They are very similar, except the upper receivers.