The adjective "manufacturière" indeed exists, but it is very stiff and formal. You may find it in a learned economic paper on the reasons for the decay of industry in the old gunmaking centres since the 1960s (and in a wider conspect in the whole country since the mid 1970s, when the "Trente Glorieuses" ended in France), and then almost always in the fixed combination "industrie manufacturière", but never ever on a gun.
As to the cartridge and chambering, a chamber cast of course will bring more certainty.
I would place my bet on a classic Lancasterpatrone (using the very old term back form the late 19th century, when nigh every centre-fire metal cartridge was called thus, in distinction from pin-fire Lefaucheuxpatronen), which were ever so popular until 1890, and then very rapidly lost followers.
English speakers of course never used this German term, they called these guns "bore rifles "or "gauge rifles".
Here, we very certainly have a 24 gauge double rifle, the last of which were produced for conservative hunters up into the 1920s. They were popular also in Eastern Central Europe (not the least for economic reasons and ease of black poweder reloading, whereas the newly fangled Nitro Express cartridges were - not without reason - considered "dangerous shtuff"). Cartridge cases existed in many lengths, and the ammo manufacturers' catalogues are full of them, with their karakteristik hemispherical bullets,"Katzenkopfgeschosse" or "Bienenkorbgeschosse", as they were called back then.
We have various threads on the those in this very forum (e.g. the "24ga Collath double rifle" thread), and an even better one in the 'Nitroexpress Forum'. Just do not mistake these typical hunting guns for the outwardly almost similar .577 Snider. The stout original military Snider load would not be suitable for those.
Carcano
P.S.: The latest offspring from this tradition was the 14,9mm Dombrowski-Heißig from around 1887, in two case lengths. A failed endeavour almost from the outset, as contemporaries already stated with some sharpness.
