Geoff, can you give us any more information? Is it marked Miroku only and not Browning? Is "FEII" the model? Does it have automatic ejectors or plain extractors? Miroku catalog copy from the early 1960's shows a Model 530 sidelock, and I have seen a few Miroku-marked sidelocks in the States (not BSS Sidelocks), but very few. A friend bought one that was a plain extractor gun. Probably should ask also just to make sure: assume you're talking a side by side and not an over and under?