As I think more about this, it may very well be the flat steel bar the stub of which pushes the safety “on” when the gun is opened on field guns. This small bar fits in a slot on the upper tang, left side, of the receiver. It may well be loose enough on some guns that it can rattle a bit. If this is it, it is fine as is. Were it my gun, I would remove the stock and barrels and see if this may be the cause.
As a side note, I think an automatic safety on any gun is an invention of the devil and won’t have one. On my hunting guns, I use a Dremel to grind off the stub as I’m too lazy to disassemble the gun and take the little bar out. I’ve done this on scores of guns for clients as well.
