That's an interesting lock, and I would consider it significant in the history of modern muzzleloading. After World War 2 until into the seventies, probably, flint locks could be hard to come by. Finding a percussion lock was not so difficult, and many were made by fitting a percussion hammer to the lock plate and innards from a junked side lock breechloading shotgun. Flint locks were another story. I remember Mr. Hamm's full-page ads in Muzzle Blasts from back then, showing around six or seven models that he produced. I think the "Maslin" lock you have there was probably the inspiration for the lock CVA produced and installed on virtually all of their guns, a few years later.
That's a beautiful lock, and it appears to be pristine. I see one detail I did not know about the Hamm locks, though, which appears to be a screw in the tumbler for adjustment of the sear engagement. An interesting feature!
I'm not really in the market for one of those, but the price is reasonable and the lock itself is a beauty. I'm sure someone will be very happy with it!
Notchy Bob