I dug my 4" Heavy Duty out of the safe this afternoon. It is in better condition that I remembered (95%+). It is serial # S746xx. I believe that this puts it being built in '49 or '50. The grips are stamped with the correct serial number. I had forgotten how neat this gun is. It is kind of like getting a new gun when you discover one that you have ignored for a few years. . I think a trip to the range is in order. Now I need to find the receipe for the load that duplicated the old 38/44 load.