Re: Civil War Era Smoothbore with hinged breech.
Also Google "tabatiere", a name given by the French to those actions from a fancied resemblance to a snuffbox. Those rifles started out as French Model 1857 rifle muskets, converted in 1867 to a single shot cartridge rifle. After the Model 1866 (Chassepot) was fully deployed, the old guns were sold as surplus. Many were bought by Belgian entrepreneurs who cut them down and reamed out the rifling, converting them to shotguns. Many were sold in Africa, hence the other common name "Zulu gun."
They were also sold in the U.S. by mail order for as little as $3.00.