My information is a little dated but if you are in Paris here is where I used to go:
Laurent Gilbert of Centrale du Fusil d'Occasion
Alex, bld de Courcelles. (
www.armuriealex.com)
H&H Avenue Victor Hugo,
Armurerie Jeannot Levallois (next to Paris and Neuilly) has already been mentioned
Armes Bastille: in particular if you like German/Austrian guns
Armurerie de la Tour Eiffel, Avenue de la Bourdonnais
If you go to Rennes, visit Armurerie & Coutellerie de Bretagne, not the biggest shop and not a great deal of old doubles, but the owner is a good friend of mine.
www.armes-et-couteaux.com
