I have a Belgian SA-22 made in the 60s, I believe. It was my fathers and I seem to recall him buying it some time in the 60s, but I can't remember exactly when. I have looked at all the flat spaces where serial numbers are usually stamped; on the receiver where it mates with the barrel assembly, and even called Browning's service department. They could not give me the location and I can't find it. Any suggestions?