No, I don't own them Larry and have never held them (I wish I did have that one in particular). You've owned a lot more French guns than I've held. But I reckon that if it is proof marked in Saint-Etienne and stamped "7.5" or "75," then there is no reason to doubt the veracity of the poinçon anymore than there is to doubt a "6.5"/"65" or "7"/"70." Here's another one from Naturabuy.Fr. Helima 12 bore with 75mm chambers.
https://www.naturabuy.fr/Vends-fusil-art...em-3404608.htmlYou'll note the 7.5/75's and higher fall into two categories:
-- they are 1880-1910 - mostly Damascus barrels
-- or are 10 bore or larger.
And again I'll refer to this pamphlet (2nd paragraph of text):
"The shells which are the most available and useful for shotguns (shooting with lead shot) have a length of 65mm for 12 - 32 gauge; But one also finds on the market shells for these gauges with a length of from 70 to 90 mm...."