unknown 14x18R propelling charge originally for a french grenade launcher but then used for a harpoon gun with a heavy price https://www.naturabuy.fr/rarissime-boite-cartouche-lance-harpon--item-1191561.html

Municion.org know it

was not easy to find anything about it, only one website showing the harpoon gun Meteor

https://www.harpon34.net/fusils-suite-3-speargun-3-fuciles-3/
some interesting old pictures with harpoon guns

like the Kongsberg gun made from an old blackpowder rifle, here the Model 1874 Gras carbine. like the greener gun only for small sea mammals like dolphins and sharks + other bigger fish

some interesting and rare pics
https://www.harpon34.net/fusils-suite-3-speargun-3-fuciles-3/

this is the second pic I ever see with the original greener gun

and this looks like the Husqvarna harpoon gun

probably for the Foyn canon

whaling gun by Devisme/Paris
unusual as possible, the barrel have a slit and the grenade bullet have a wing that get a spin by the slit in the barrel
the wing will be connected with a rope

whaling gun by Charles Osborne&Co