I'm curious to learn about this one. Kauffman's book refers to a quite specific type of lock to which the term "hand-made" had become commonly applied by the time he was writing, which of course was a long time ago. He speculates that those locks may have come from Germany, which is why they would possibly have been preferred by the German gunsmiths in PA. He also identifies them as distinct from the Ketland locks also seen on contemporaneous rifles. As someone in PA interested in PA rifles, I'm also very interested to know what we have learned since Kauffman's rather speculative musings about the origins of the "hand-made" lock.