Thanks George. I forgot to mention having it inspected. John is correct about this maker being all over the place in terms of quality. Janssen was involved with several other makers in various collaborations. They did produce some very nice guns.
This is a Janssen from the link I provided above to Littlegun. Also a hammer gun.
The lack of flats and cupped receiver seem to be common. A Janssen of this quality was not the best of the litter. If you want to see a top Janssen, then Adolphe was the maker to choose:
http://www.littlegun.be/arme%20belge/art...dolphe%20gb.htmPete
