Yeah it's the same idea. No idea if it was converted or made that way. But unlikely a pinfire cartridge would work with it.

I have a handful of these, some of which are US patents.
[Linked Image from photos.smugmug.com]

I did a short article on these some time ago, focusing on the pistol cartridges. This gun had an insert that allowed it to work also with pinfire cartridges. And some had a very tapered "pin" to allow it to work in existing 12mm revolvers:

[Linked Image from photos.smugmug.com]

Clock Guns, Pauly Guns, Pinfire Guns and Pinfire Cartridges