Interesting research Argo 44. The gun is question is made by Blondeau who make these guns for most of the French dealers in all shape and sizes, even sidelocks. When I saw the picture I immediatly thought about Blondeau and to be sure I attach a link to a gun who is for the moment for sale at Natura Bay, here is the link:http://www.naturabuy.fr/adsearch.php?title=2850361
cheers, Marc.