An old Dutreuil thread on Shotgun World
http://shotgunworld.com/bbs/viewtopic.php?f=5&t=429133

and here
http://www.doublegunshop.com/forums/ubbt...e6172d7d6ab57c4

It was made 1910 - 1922 (no lettre annale) and does carry smokeless proof.

With the 2 muzzle constriction over bore markings on the right (only?) barrel it may have been reproved after honing

'JC' could be Joseph Cap
http://www.littlegun.be/arme%20belge/artisans%20identifies%20c/a%20cap%20joseph%20gb.htm

PeteMs list does not have a 'NW'