Dont listen to these guys. They are all in on a conspiracy. Once you get AV'd you will find tonnes of full metal glocks and G36s.
Just kidding. But seriously, you even knew the real steel is my from polymer. Why would any airsoft manufacture make a full metal one? But FYI, some models do have metal inserts where it counts to help reduce some potential body flex. If I recall corectly, my CA G36 has metal reinforcements in some places.