.
As mentioned, there are some pretty good Spanish shotguns, and there are also cheaper, low end ones. Back during the 1960s era, the Americans wanted economy shotguns with more to their taste features, such as larger pistol grips and beavertail fore ends. Then, engraving too. This added to the cost of the gun to the gun maker, so he had to find out a way to reduce items so he could at least make a profit. Consequently, quality suffered.
However, some of the Spanish gun manufacturers kept up a good quality firearm, along with some cheaper economy guns. The Spanish gun industry did not produce a lot of shotguns, because there was many makers, particularly in the Eibar region. Most of the shotguns turned out had a lot of hand fitting on them, so production was much lower than ones stamped out by machine such as the Remingtons, Winchesters, Stevens, and such.
You also have to look at the purpose of the shotgun you wish to buy. If you are going to bust a lot of clays, then the better quality guns were made for a lot of shooting so they are made a bit heavier and more detail went into them, and the price skyrocketed when you had one made. The ordinary shotguns were designed for game shooting, so could be made a bit lighter and trimmer, and are a joy to shoot. Today, if you walked into a Spanish gun makers shop, you had better have about 5 grand in your pocket, and that is just a start. Today, the Spanish "Best" guns are well respected and even the old time English famous name gun makers respect them as equals.
For upland game, with LEAD shot, the Spanish side by side is more than adequate, but if you are hunting WATERFOWL, using steel shot, forget it. Those barrels are not made for steel, and are a bit thinner than todays shotguns with screw in chokes. For over 40 years in the west, I used a 20 guage Spanish shotgun and when I left Alberta, the Pheasants, Hungarian Partridges, and other Upland Game birds held a big party and breathed a sigh of relief.
Also, the degree of CHOKE in the barrels differ a bit in thinking in Europe. Many times the right barrel is more open, such as Improved Cylinder, but the left barrel is a much tighter Full or Extra Full choke by our standards. I do not consider this a problem, because I pattern my shotguns so I know what to expect. In fact, I like to think of it as practical, for a close rising bird, and the second barrel for one farther out (or a second farther shot at the same bird because you missed the first one.)
If you post good close up pictures of the markings on the water table, (the flats on the action where the barrels rest) there is a lot of information there, (also the undersides of the barrels themselves.) The Spanish gun industry has some of the best proof firing tests in the world, and this information tells you the maker, the date code, and the characteristics of the barrels themselves.
Right now, there are seven Spanish double side by sides in my gun rack, with another one on the way here.
GOOGLE is your friend. Pedro Gorsabel made several models, the numbered ones were box lock and the names were sidelocks. Try the internet, Google "Gorsabel" and you will get a lot of information.