The guns with the worst reputation were made in the mid 1970's from my experience. That said, any gun which has seen decent use over 20, 30, 40 or greater years should be fine. I would be cautious of a safe queen which has not been shot much over 40-50 years. I have seen a couple 12's which seemed as new and had been stored in a safe because they frustrated the owner due to issues. I had a gunsmith who had worked on hundreds of these guns and he would harden several parts on a routine basis to eliminate issues. He said it was a hardening issue, sears, firing pins and hammers I recall, more than anything else and once properly hardened the issue went away with just a little fitting. Sadly he has passed away so he is no longer an option. But on Spanish guns, even in the 1970's era I suspect all the issues have been fixed for the most part with the exception of the few "un-fired" safe queens. Look for a gun with obvious use but not abuse and be happy. The previous owners have made sure the issues were fixed years ago so they could shoot them. Nobody can stand to shoot a gun which does not work on a regular basis. It gets fixed or sold down the road until some owner does fix it properly or screw it up so badly it becomes a parts gun. I have seen both examples. And I never saw a 28 or .410 with issues, I am sure a few exist, but the ones I knew about were mostly 10, 12 and a few 20's.
