Sten: Thanks so much for the additional photos. I agree with Philip that it appears to be a locally made native copy. And that it is still in working condition is even better. As I mentioned, this is only the second time I've seen this style lock mounted to a gun. By the way, I too like the sling on the gun. The whole gun has a very "tribal" look to it.
Philip: Thanks again for the great information on this lock style. Most interesting.
As a side note, here is a new made copy of a Portuguese style gun utilizing a similar lock style. This was built by a contemporary maker here in the USA. He has agreed to make another lock (only) for me, which I could utilize on a shooting gun.
Rick