i got a old Smith M+P but have never owned a Smith double action so have a couple questions. First i have a number stamped on the bottom of the grip frame(square butt with a lanyard swivel) and different but matching numbers on the crane and frame. Can i determine this gun's age with either of these numbers and if so where. Walnut grips,k frame,38 special,fixed sights,slender barrel profile, firing pin mounted to the hammer,stamped US property GHD...the bluing is pretty much browned, but the action is tight,very smooth double action pull, no buggered up screws looks to be 100% original. I think it's a pre-war m+p but am not sure......