Wow, SNAFU'd by over-exuberance again! I was poking with my trembling finger... getting ready to ask where I could buy one of these guns! Then I realized the pictures were some of Kyrie's secret stock of best guns! He just uses them to make the rest of us pine for the good old days, when such things resided in pawn shops.
You're going to have to come up with a maker's mark buddy. I've seen Universal 221 listed as armas Erbi, Zabala, and Ugartechea.
Shotgun porn :-)
Seriously though, there are still a great many high end Spanish side lock shotguns that come up for sale here in the US, and go unrecognized because people dont know what they are looking at. Last November I came across an Armas Bost medium game gun (equivalent of an AyA model 53) on Gun Broker. That gun sold for $800.
At the moment there is an outstanding Spanish side lock on offer on Gun Broker, described by the seller, as a Felix Sarasketa. I think I know that gun and, if Im right, its actually an Industrias Ilja that was retailed as a FS. Seller wants a minimum of $1825 for it and is running 24 hour auction after 24 hour auction, and getting no response.