Yeah Ive totally stole this thread, but I have to disagree, show me a reference for Duckbill locks? They are dipped edge locks either the Rogers action or modified or improved Rogers action. They were the cats meow in the late 1880s and widely used throughout London and Birmingham. They were improved upon as all things are, aside from the bespoke makers who developed their own locks there is nothing written about them being on low quality guns or widely out of fashion, they were used on guns of all grades, besides show me a low grade/quality keepers sidelock from a London maker? My guess is you will find them on Best to mid grade guns.
