Sofar i have been unable to find any other locks belonging to this type of gun.
My best guess is as follows (see picture):
A rectangular lock plate with an early tumbler and sear mechanism as seen on flintlocks. The black parts are the springs, the red part is the tinder holder.
A similar mechanism can be seen on a 1530-40s snap tinder lock.
Will keep looking, any help in finding more of these guns is appreciated
