There was plenty of barrel making technology available in Saint-Etienne. Sure at times Belgian barrels were used in some Saint-Etienne guns...For instance Neltir said Zaveterro Frerres sused (Belgian) Lovinfosse Hardy François et Fils barrels (1930'a) - but it was demonstrated that ZF also used its own barrels and those of Society Heurtier also from Saint-Etienne. The Belgian barrels apparently infiltrated because of price. however, these barrels have proof marks and maker's marks. Belgian barrels have Belgian makers' marks and proofs. If the barrels are proofed in Saint-Etienne...assume they are French.
I agree with Larry - I think the barrels are Saint-Etienne; the stock is not original.
Here is a very interesting line on a Saint-Etienne G. Callens gun which discusses Belgian pricing..including comments by Dr. Drew Hause. You'll note that the comments are congenial.
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=368629&page=1
