Interesting subject, thanks for posting it. Such guns were also made and used here in the American Midwest, especially along the Mississippi and Illinois Rivers, which abounded with waterfowl. I know of a couple of them still owned by people in this area, both percussion and both dating from the mid-19th Century. Both are unmarked as to maker. There were some of these made on into the breech-loading era, usually 4 -gauge, using huge brass shells.