Even better. This, technically, is not your problem.
The chambers issue is irrelevant. The relevant point, as Kyrie has duly noted, is parts are not interchangeable on Spanish artisanal shotguns.
Full stop. Go back and read it again.
There is no warehouse full of fully fitted spare parts for old Spanish double guns. They were typically built to order, with the internals fitted by skilled labor. A gun fitted up on Monday would have no interchangeable parts with one finished on Friday. This was a cottage industry, with suppliers turning out rough parts for a manufacturer that then fitted them by hand. In later years, some of the manufacturers might have had higher production of models that featured production machining, but, your gun is not in that group.
Noted by no one at this point in the discussion is that barrels are literally the heart and soul of the gun. If they aren’t there, you are facing a huge, uphill battle to get even a machine made gun (think Beretta, SKB, Savage, etc) up and running, more so if the gun is obsolete. An artisanal gun, from a small, long gone maker will be close to impossible. Were you to find a set of compatible barrels you would need to enlist the services of a good double gunsmith. This guy is not the same as the guy who blows chokes open from the front of Mossberg 500 barrels, and replaces parts on similar guns. He has a skill set that doesn’t come cheap.
All that said, good luck. Impossible might be too strong a word, but, you are pretty close to it.
Best,
Ted
