Mon Dieu Aaron. Keep that in your house, the bomb squad might come knocking.
Tried looking up "Gevelot, Paris" and this popped up: "Société Française des Munitions; Ancien Establishment Gevelot & Gaupillat, Paris."
https://fohbcvirtualmuseum.org/galleries/target-balls/gevelot-paris/Founded in 1820 in the Paris area, Gévelot started out manufacturing the sabers for the Royal Gendarmerie at the beginning of the 19th century. In 1823, Gévelot received authorization to use fulminate of mercury in the manufacture of primers and to make cartridges. This authorization was renewed by Ordinance of Louis-Philippe, King of the French, in March 1845, then at the end of March 1852 by Louis-Napoléon Bonaparte, President of the French Republic. This production of ammunition would continue all the way up until 1980 and forge a worldwide reputation for Gévelot.
And this 8 bore pin-fire cartridge:
https://www.wardscollectibles.com/auction/A93/viewitem.php?item=5397Here is Gevelot "Our History:"
https://www.gevelot-sa.fr/en/about-us/our-history/This is a super interesting page on European cartridge France/Germany head-stamps, which Aaron might even have authored; I've book marked it.
https://cartridge-corner.com/shotgun3.htmI had to stop - the urge to collect suddenly came over me.