One thing that has been left out of the discussion is the wear on the pin and hook caused by the physical act of opening and closing the gun. It has always been my understanding of the things that the pin was harder than the hook, and that wear on the hook was usually the cause of any looseness. Over a period of decades, shooting thousands of rounds, under sometimes less than ideal conditions with poor lubrication, wear on a gun will happen. If a gun is lubed correctly and shot with the ammo it was untended to shoot it will outlast the shooter. Pick up a 100-year old Parker with some wear: generally the action will wobble. But I'll wager the thing digested many many rounds of Super-X before wear became apperent, along with being opened and slammed shut with each round shot. And I'll also bet the reason "modern" guns do not seem to exhibit the same issues is they have simply not been around long enough. That and modern metallurgy. My $.02.