"Spanish Artisanal Shotguns" You sound like "Beans" talking about LC Smith guns.
Just a couple of comments on this subject. When it comes to a gun makers finished product, the maker themselves is solely responsible for the heat treating and overall QC of the various parts they have sourced throughout the trade whether that be forgings, castings, barrels, wood, etc. If the gunmakers are getting inferior parts that don't meet quality standards (type of steel, etc.), that's on the maker to take care of by dealing with that vendor. If the gunmaker is sending out a finished gun that has parts that are not properly heat treated or made from the correct grade of steel, that's on them.
Just to drive the point home, no gun-trade parts makers or vendors send parts out that are already heat treated. Heat treating happens after the parts are fully machined, shaped and fitted. Sending out heat treated parts like actions, forend irons, ejector bits, tumblers, locking bolts, spring blanks, etc would be counter productive seeing how heat treated parts are a pain in the ass to machine, fit and otherwise work with. It would also add in the extra step of having to spend valuable time annealing everything to a soft state so it could actually be worked on. As many gunsmiths will tell you, hardening a part is only part of the process, it'll also have to be properly tempered and "drawn back". If you've ever had to make any parts or tools, you know exactly what I'm talking about.
The Spaniards could always harden steel with the best of them, the proper methods of tempering & drawing back is where they fell short and for some odd reason, they (the so called Artisanal makers) didn't seem to care all that much. Who knows, maybe when that part of the process at some of these shops was supposed to take place, it just happened to be right on the cusp of "Siesta" and they just never really got around to it or they just didn't care all that much. If you've ever lived in Spain, you know what I'm talkin' about.
