Belgium gun makers

[P51mustang]

Howdy,

I recently acquired a target pistol by a Belgium gunmaker named Adolphe Jansen who is "gunmkaer to the king in Brussels" The target pistol is marked with a number 2 suggesting that it started life as a matching pair. Is anyone familiar with his work or the work of other Belgium gunmakers of the mid 19th century? Also, if you happen to have the same one with a 1 marked on it let me know lol.