There are several here who can help out..Larry, Ted, Bétail enlisé aka Wild Cattle (he's always swamped with work), and several others. I'll offer couple of comments which might help, (sorry if this seems simplistic but I sort of have to walk myself through this occasionally - there are experts here who read this stuff like Brail or Breuil).
Here is a line where we began to try to date late 19th Century, early 20th Century Saint Etienne shotguns:
http://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=484199From that line your gun was made and proofed in Saint Etienne; it is post 1900 (proofed for PT) and post 1912 (chamber maked in mm rather than cm).
I would like to have some clarification on what is written in block "1" and block "2".
-- Normally block one would be some sort of advertisement/hype..."Canon sur quoi" or something but I can't read it. My Gerest Berthon had “Canon du Surete Garantie” “Double Express” in this position.
-- Block 2 is normally just "choke rectifie" which essentially means nothing but there is a name attached to this one that I can't read.
The barrels are originally proofed for two palms, not four. Also where is the Breuil name on the barrels? Here are two historic stamps used by Breuil:
Stamp used pre 1912 in the cm chamber era:
Stamp used post WWI:
Once this is addressed, we'll start looking for "AB" because that is who built the gun. It's on the barrel and the key.
The French seemed to have gotten into engraving the makers name onto the key...partially because of Verney Carron's patents and reputation. Here are some examples. (And the name "Helice" is generic and was never patented by VC)
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Just as an example, here is a 1906 Didier-Drevet barrel on a 16 gauge Gerest Berthon which I marked up for my Daughter in law to whom I gave the gun:
1. Didier Drevet, barrel maker (Canonier St Etienne) and his marks.
2. Grand Prize 1900 (for Paris Universelle exposition) (Gerest won a gold medal there and I think this is for Gerest not DD. DD won a prize at Liege in 1905 and there is allegedly a mark on the gun to this effect.
3-4. Once again the Proof mark for Saint Etienne for PT powder.
5. This is the length of the chamber in centimeters i.e. “7 cm” or 2 3/4”..normally marked 70mm in every other place in Europe but Saint Etienne at the time… Saint Etienne switched from using mm in 1889 to cm then back to mm in 1912. The fact that this gun is chambered for 2 3/4” is unusual. Most French guns of the era until after WWII were chambered for 6.5 or 65mm i.e. 2 1/2” shells. See “Double Express” on both barrel and butt plate.
6. 17.0 = diameter of the bore in mm which is equal to 16 gauge in America/UK. 18.4mm is 12 gauge. 15.6 is 20 gauge,
7. The crossed palms with “St Etienne” is the Saint Etienne proof house mark. This gun has two palm marks, meaning it’s been “double proofed” for more powerful powder charges than normal. The old butt plate which was replaced had “?????? Express” stamped on it.
8. “Didier Eureka Canon Plume”: trademark of Didier Drevet. He invented a barrel which did not have a lower rib and thus was a lot lighter. Canon (barrel) plume (feather) is the idea.
9. “Non pour la balle” (not for ball). This means that the barrels had “chokes” and could not fire a straight slug bullet the size of the bore.
10. 7859: Gerest-Berthon serial number of the gun
11. “Canon du Surete Garantie” “Double Express”: Sort of an advertisement meaning “guaranteed good barrels.” The “double express” is interesting and unusual as mentioned above and is why it’s chambered for 7.0 cm length shells.
12 (white). 1906 . 11985: The date the barrel was made by Didier Drevet 1906 and DD’s barrel serial number. Saint Etienne guns are very hard to date. However, the fact that DD dated and serial numbered his barrels enabled me to sort of revolutionize the dating process….
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I'll add that quite often on the bottom of a gun made in Saint Etienne you'll find the name of the retailer. On yours that has been replaced by the engraving: Here is the retailer of my daughter-in-law's Gerest Berthon:
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And if push comes to shove, I'll figure out a way to post it onto
www.Passionlachasse.Fr. Ive joined in a couple of times but can never seem to get a post to go through.