Steven, what Adirondacker is saying is your gun is a .32 Regulation Police revolver with a serial number around 400,000 (mid-1920s). The SN is stamped on the front of the grip frame because the rebated (round and notched) frame is 3/4 enclosed inside the grips. The grips are a type of round to square butt grip adapter. Square butt is the correct technical term. The barrel is 4-1/4".