This is a cross post from Shotgun World and 16ga.com. I was told you guys know your stuff. So here goes.

A customer brought this into me for a cleaning, ID, and appraisal. I know little about it other than it is a 16ga, has 27" barrels, and 2.50" chambers. Other searches I have done have not turned up anything of substance.

I think it is a french gun. It hase on the action in what appears to be gold inlay "Martin A Paris" Which turns up nothing in my searches. On the flat of the reciever it is stamped "Denis. m". The only common thread to this gun is the Crown stamp over a "PT" stamp. All of the cross pins in the reciever seem to be rivited and not threaded with heads on them.
I need to find out what, when, where, who, and how much. What is it pressure rated to? Customer want to shoot it if he can. Otherwise it will be a wall hanger or sold if it is a very high dollar piece.

Also it came in a leather case stamped P.D.V.

Here are the pics.