Parabellus
.410
I ordered this rear sight for my Mossberg 500 20 ga. with bead front sight so I could use it at the local range which requires all shotgun have sights for use on the rifle range. Lo and behold the screw is too small for the screw holes along the top of the receiver. The base of the sight is curved nicely to fit the curve of the top of the receiver but it can't be screwed down; the screw slips right down the hole. What do I need to make this work? Is there a low profile curved rail for this? Epoxy?