"Buxton's Guide" (from 1963) shows a Miroku Model 530 sidelock with more engraving than that one. My hunting partner owned a pre-Browning Miroku sidelock a few years back. Extractor gun. The only other one I've ever seen was a 12ga at the KC Gun Show over 10 years ago. Probably should have bought that one, for half the price of a BSS Sidelock, but I was not looking for a 12 at the time.