Well, I got the top screw off. It's not a top screw at all. No idication that it ever had threads on it. But, I'm 90% sure I know what it is. It's an iron tip from a ramrod from a Moroccan gun!!
What look like two sets of threads are not threads. The are straight cut to assist the shooter's grip while pulling the ramrod from the rifle. I've seen this design on iron ramrods on other Moroccan rifles. There are traces of threads in the lower jaw. I can see where the one end was cut and ground/filed and tapered. It was simply hammered into the lower jaw and the tiny tit on top of the hammer was bent slightly sideways to hold it all together. I bent the little tip straight again. Then a couple light taps with a hammer and it came apart. Amazingly, the patina of the "supposed" top screw matches the rest of the lock. So, what we have here is a lock in very good condition, thats missing it's top screw.
Usually when a lock is missing a top screw, it's also missing the top jaw. My best guess is that someone used the original top screw on another gun. Well, unless others disagree, I think I've solved the top screw mystery (?). I must admit it was fun. Fortunately, I have a spare Moroccan "parts" lock that still has it's original top screw. I think I can clean up the threads in the lower jaw to accept it. Rick.