Just to clarify (since I got confused)....we are talking about two different guns on this line.
1) A 12 gauge SxS 12 bore, Saint Etienne. It is possibly missing a forward section of the barrel. And it has some Belgian marks on it as Raimey and Tom both commented. Here are the proof marks and there are some strange ones I'd never seen (circle with a "C 1 2" in it, for instance) (and "Forage" - barrel drilling - D 1/2") - so much so that I made copies of them for my notebook:
2). A 16 bore "Berger" "Helice" with the "Frond M M Frond" proof and no Belgian marks at all that I can see. Whew - might need another vodka tonight.