Raimey, my digital camera fits in my shirt pocket, the photos aren't the best.The numbers read, left to right, 1900 and 8975. The guns serial is 759, that also appears on the under rib.
The oval, on the underside of the right tube, in back near the lug, has a crown with the initials DD and a tiny star under it. There is a tiny triangle with a D in it on the other side? Didier? Maybe.
"Acier Mandrine" would lead one to think mandrel drawn steel tubes.
Assuming the 1900 is a date, I'm not sure why one would go back to powder M for proof, unless the tubes were made and proofed a few years prior to being used.
It is a sweet handling old gun.
Best,
Ted
