The NRA Blog writes …
One of the most unusual repeating firearms ever to be manufactured in the United States was Isaiah Jennings’ repeating flintlock rifle of 1821.
Built with a detachable skeleton-type shoulder stock as well as a removable 21-inch octagonal barrel, the Jennings rifle was capable of firing twelve shots without reloading. This multi-shot arm was loaded with a dozen superimposed bullets and alternating powder charges, each placed one on top on another down the bore, and was fitted with twelve individual touchholes, each also being equipped with a swivel cover.
More photos of this intriguing rifle here.