I'm not sure where to buy them or what kind they actually are but my NEF 10ga has rifle sights on it. I bought it at a local gunshop like this. The holes for the rear sight match up with the tapped hole in the barrel from the factory. As far as the front sight I think they may have had a gunsmith drill and tap a hole unless there was a hole drilled and tapped for the original bead. I think a gunsmith would be your best bet.