I'm sure this topic has been discussed As Nauseum, but here goes - I have always heard that there was a period in Spanish mass markiet gun making that suffered from poorly heat treated parts and resulting soft components. If true, when did that occur?
Yes sir, that's a subject that has been done to death. It's also a subject on which there is more myth than substance, because it's complicated. Nothing about the Spanish shotgun 'industry' is anything other than complicated. I'll give this a shot.
Firstly, there is no such thing as a Spanish shotgun industry, nor is there anything like a mass marketing of Spanish shotguns. With some isolated exceptions, all Spanish shotgun makers are small businesses, with only a few employees (AyA has at present fewer has twenty employees and a visit to their shop will only find 10 or so working at any time) and some are/have been single man shops. Again with isolated exceptions, no Spanish shotgun maker actually makes all the parts that go into the shotguns he assembles.
Rather the structure of the shotgun business in Eibar is almost exactly like the shotgun business was in London, in the late 1800s. At present there are, to the best of my knowledge, only two makers of shotgun barrels in Spain. All of the shotgun makers buy their barrels from these two barrel makers. There are perhaps less than 3 or casters of locks, frames and other items that require forgings and these are individual artisans. Most engraving is done by local artisan contractors. There is only a handful, maybe less than 10, engravers in actual employ by the makers. In short, we have small independent business dependent upon a few parts suppliers and essentially all assembling guns to different styles from the same set of parts.
Spanish shotgun makers are shotgun assemblers; they hand fit parts obtained from an informal network of parts and assembly makers into shotguns, and stamp their names on the resulting guns as the 'manufacturer'.
Historically, when one of these makers received an order for fifty or a hundred guns from a US reseller (hardware stores, importer/resellers, etc) there was the potential that the maker would have a hard time meeting delivery deadlines. Many of these Spanish makers didn't produce fifty guns a year, total, and their suppliers of parts/assemblies couldn't supply the parts/assemblies to make more guns than that. What sometimes happened is the US buyer would push the maker to meet delivery deadlines, and the maker would push his supplier to make and deliver more parts/assemblies. In some cases the parts supplier could only increase the number of parts delivered by reducing the time it took to make a part or assembly. Sometimes the first corner that was cut was heat treatment on some of the parts delivered or more commonly, younger, inexperienced people were hired to do the job and the hardening just wasnt done correctly as would have been the case with an employee with years and years of experience.
So we have cases where some soft parts/assemblies are delivered to and used by the maker to make shotguns. Shotguns are delivered to the US buyer and sold to US customers. Of the customers who got guns with one or more parts not heat treated, problems begin to develop in a month, or a year, in ten years, depending on the part and the amount and type of use.
The level of complexity in the parts makers/gun makers relationship is difficult to convey, especially to a US audience accustomed to thinking in industrialized terms. The Spanish shotgun makers are not industrialized; they are small shops who largely work without even power tools, at a blacksmith level of technology. They are artisans, not industrial workers.
All that said, the 'isolated exceptions' need a few words. There have been companies who attempted and largely succeeded in actually making all the parts they used to make shotguns. Victor Sarasqueta was one of these, as was (arguably) the AyA that existed before DIARM (the post DIARM AyA is a small shop). There was a time, before DIARM, when AyA made enough parts to have parts surplus to the needs of AyA, and sold these parts to anyone who could pay for them (AyA essentially acted as a parts supplier as well as a maker). The present day AyA would, I think, like to return to those days. Whether or not they will succeed is unclear.
