You have a true un-used sight. The ring sight has no hole until it is drilled and pinned when fitted to the barrel. All of the sights we see with holes in them are take-offs. When the sight has no hole its easy to drill thru the sight and the barrel. If there is a hole, the tip of the drill skids off the round surface of the barrel. AOC is, of course Auto-Ordnance manufacture. This is an original sight. Bob