YIKES! STOP WHAT YOU ARE DOING! Make sure if you move that sight back and forth that you completely removed the wide screw on top of the sight. That screw is designed to fit into one of the recoil arresting holes in the top of the receiver to keep the sight from sliding under recoil. If you do not remove the screw completely you 1) run the risk of dragging it across your new bluing and leaving a scrape and 2) you cannot look through the screw hole to align it perfectly with one of the recoil arresting holes underneath before tightening down the scrw and you risk the edge of the screw catching the edge of the recoil hole and buggering up the hole. Also, DO NOT tighten that screw down on the receiver. Position the sight so the screw goes perfectly into a recoil hole.