Doug: the 'JD' mark on the barrels looks like that of Jean Duchateau
http://www.littlegun.be/arme%20belge/artisans%20identifies%20den/a%20duchateau%20gb.htm That is indeed 3 Iron 'Turkish' and appears to have been acid etched (can you feel the pattern?)
It was made 1898-1924 and does not have the Lettres Annales (Dateletters) which started in 1922.
The numbers on the left barrel are the bore size and choke constriction in mm.
Please note it does 
not have the Optional Smokeless Powder proof used 1891-1924.
Edit: what Travis said 
