am a new member and I think this is wonderful. I have a model 12 and have learned a lot of information on my gun. I also was reading the posts on these guns. I have one of these and have had it since I was 9 years old and knew nothing about it for years. The wording on my gun barrel is FARRIOUT NATIONALE DARMES deGUERRE HERSTAL BELGIQUE.
What you have is a single shot produced by Fabrique Natilonale d'Armes de Guerre, aka "FN," the same venerable firm that produced the Browning Hi Power, A-5 shotgun, myriads of .25s, .32s and .380s, etc.
Not sure if yours is one of the ones designed by John M. Browning or not. He sold patent rights to Winchester for a cheap, simple .22 single shot, but I don't remember what his arrangements with the FN firm were regarding .22s.