Sorry OP....I forgot to add my CS story.
Several years back I bought a used FA from GunBroker. After I got it the mainspring needed replacement as the action was simply not quite right.Seems he'd had someone "tune" it.
I ended up sending it back to FA and they replaced everything I needed, and went through the entire gun, checked everything out. ...the price was so small I forget... $30? $40?
The guns are built so stout that unless someone gets into the action and screws up the tune...very little CAN go wrong with them.
Have a Buddy in PA who has several. As a matter of fact, He just bought a new one yesterday, a custom octagon barrel mode 83 l with dual cylinders. He has visited the factory as well as had a bit of a relationship with them for several years. he has never had any issues.
I think one can buy with confidence from FA.
FN in MT