I have what I think is a prewar Walther PPK in .22. It has a serial number of 242020K. It has only Crown N civilian proof marks. No military stamps at all. It is in high gloss blue with wrap-around grips. I looked at the available generic serial number charts, and they seem to indicate 1939 or 1940, which would be wartime production for Germany. I am unsure if those serial number charts are for 7.62 only and there are different charts for .22s Can anyone here help me out as to year of manufacture? And if it is 1939 or 40, why it is not military marked? Much obliged.