Welcome Tom.

This shows the St. Etienne proof mark was not used until 1897. Obviously the gun is much older. A French expert might explain.

[Linked Image from photos.smugmug.com]

The Crowned 'BD' is very likely a maker's mark; possibly the Liege tube maker Bauduin Doyen of Fraipont. The barrels are Twist/Damas Rubans.

[Linked Image from photos.smugmug.com]

I can't fit these letters with anyone here. 'LRD'?
http://www.littlegun.info/arme%20francaise/a%20accueil%20arme%20francaise%20gb.htm

[Linked Image from photos.smugmug.com]

Do you know when the cracked stock was repaired and refinished?