The original Single Six had a partial steel frame, and partial alloy parts. I know the stainless Single Six is all steel frame. Is the New and/or Super Single Six in blue all steel or still partly alloy? Can someone give me history on this please? When were changes made, etc. Thanks. I know that original or "three screw" do not have the transfer bar safety. I know that the "New" denotes the transfer bar. What I don't know about is the frame material.