Thread: Another lesson under the belt - parallax binding up

Talleys make an alignment bar for setting up their rings, without using it you are reliant on a bit of luck in achieving perfect alignment as there is firstly the possibility of improper positioning of the screw holes in the receiver, and secondly you are reliant on the heads of the fasteners to locate the bottom half of the ring. These fasteners (shank and head) are a clearance fit in the screw holes as per normal engineering practice, so you have the possibility of misalignment occurring at that joint. The alignment bar has a slot milled in it so that you can fasten the mounting screws while the bar is still in position. I have a 30 mm alignment bar (a 1" alignment bar is also available) that I have used on 3 separate guns with success without lapping and not causing ring marks on the scopes. When you lap rings material is being removed with the rings in a specific position, the quantity of metal being removed to make a good fit being equal to the amount of misalignment present. If you remove them and remount them this position may not be repeatable, however you may also find this process may be effective.