[Nova Receiver?]

Thank you. When you say a polymer over a metal frame what do you mean exactly, is it a metal skeleton or something else?

[Nova Receiver?]

I am interested in buy a Nova and can not tell what the receiver on the nova is made of. I understand that the receiver and the stock are one piece and that the stock is a synthetic but it looks like there is a seem between the upper and lower part of the receiver, is this correct? Also if this is true what is the upper part of the receiver made of?