22LR model can be found on the right side of the handgun. There's no way to be sure, but I think it was made by Smith from left over Interarms parts or was a finished gun, but not stamped, when Interarms ended it's corporate lifetime. The serial number of my PPK/S is XXXXAAA and it's stamped Walther USA LLC, Springfield Mass. The bulk of the proof stamps on this Walther PPK Interarms Walther Ppk Serial Number Lookup.German Walther Ppk Serial Numbers Chart.
