You can put them through alot and they just keep working. One of the ones that I have started as a trap gun with me but then carried it exclusively for pheasant hunting for several years. Its also been used as a waterfowler, turkey and crow stopper. Even done some live bird shooting with it due to the constriction it has. Then my son decided he wanted to shoot trap with it and he used it for 3 or 4 years before quitting the game. The only thing that I remember breaking in all that time was the bottom ejector.
The most fragile piece I found to be the ejector extension. Probably put 75,000 rounds + thru it and broke one. Went back to factory to be tightened up once but that's all. A real workhorse! Mine was a '65 gun and the fella that owns it now just keeps shooting it. Sort of wish I wouldn't have parted with it.
I have a pair of Superposed Lightning o/u trap guns. Still tight and no problems. I replaced a firing pin but that's it. 1 is 1969 and the other is 1970. I don't shoot them anymore if anyone's interested.