I have an Ares M4, the back of the receiver where the stock connects to the receiver, snapped (it is aluminum).
The Ares M4 takes real steel stock tubes and I'm having a hard time finding a brand that makes a receiver that will fit. All the receiver i've seen for AEG's have that stock tube sticking out.
These are the ares bodies. http://aresairsoft.com/mbody.html