the 24 barrel .22 lr volley gun is clearly named "canardiere" what is the french equivalent for punt gun so it was fixed on a boat and used for shooting geese at long range.
I am looking for a while for punt guns outside of great britain. know it for sure this was done in France and Switzerland maybe also in the Netherlands and Belgium. the 4 bore pinfire fowler I saw in Denmark telling its maybe possible they do it there too and Fiocchi in Italy was making the 32mm puntgun cartridge.

Punt guns became forbidden in Switzerland in 1962 but some areas were lazy so it last some time after.

here is a muzzler loader in a swiss mueseum, forget where I found it

here a 1,5" / 37mm french Manufrance punt gun in the Swiss Hunting Museum Schloß Landshut
http://www.schlosslandshut.ch/index.php/galerie.html

the bycicle trigger was a modification made by the last owner

older french muzzler loader fowler between 12 and 4 ga are very common but it was maybe under british influence they go to realy boat cannons. Manufrance made them in caliber from 4 ga up to 1,5" or 37mm

some saw action as fighter airplane gun

nice old postcard showing a french punt gunner http://images-00.delcampe-static.net/img_large/auction/000/321/822/752_001.jpg

think this is from Greener's book "The Gun and its Development"

http://www.freerepublic.com/focus/f-chat/2989145/posts