I'll have a go...will have to do some research on the proof marks with an arrow. I don't think I've ever seen that on a Saint Etienne gun....strange.
It's a ManuFrance Robust. Model 32-E-S. Below is a chart which details when the various Robust models were made from this line:
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=484199&page=11If I read the chart right, that model was made in 1930 and 1931.
Here is the definition of the various bits of stamps on the gun:MF in laurels/ Saint Etienne logo - Manufrance
Crossed canons with arrow logo - Manufrance
PT - proofed for smokeless powder (first appeared in 1900)
Cal 16 normal - 16 gauge (normal may refer to the chambers which would be 65mm, since chambering is not marked on this barrel).
Choke - choked
Raye - rifled (there were also shotgun barrels which had groves assisting the spread of the shot that used "raye.")
Interieur poli en long - groupement garanti: Interior of the barrel polished for its entire length -shot grouping guaranteed.
Epreuve du fusil fini - finished gun proofed at 1100 Kilos
Fusil Robust Brevet S.G.D.G. - Robust long-gun patented
Fabriqant Mecanique - means nothing - mechanical fabrication
Canon Frette - monobloc barrel
Acier Hercule - advertisement - Hercules steel - means nothing
I don't see a chamber stamp....this should be 65mm (2 1/2") (i.e. "normal")
I have been told that the top safety on Robusts did not appear until 1930, which would match with this model having been made 1930 and 31 only.
Also there is a chance that a physical date the gun were made is under the butt plate stamped into the wood.