The one piece back action flintlocks were Belgian musket locks originally, later they were made for the African trade. These later productions date clear into the early 20th century. the two piece locks of the same design were built mainly by Century Arms in Belgium for the replica market. Many of these replicas were not designed to be fired. But, a lot of them were fired, and an amazing number survived. A friend has a trade gun built with the two piece version of this lock that preforms pretty well.
Dixie Gun Works marketed a big bore musket, in the sixties, and early seventies, that was called the elephant gun. It used the two piece version of this lock.
Hungry Horse