If the Rifle shoots groups, but the groups are either to the left or right, you may be able to buy or make a new rear sight, and file the notch either left or right of the original. Your a Skilled Machinest, you may be able to take a rear sight and drill and tap two small screw holes in it, and take a thin piece of metal, and slot the holes where you can loosen the screws and slide it left or right on the back of the sight, and cut you a V in the top of it for a sight notch. you would be making a windage adjustable sight. Similar to the stock rear sight on a Ruger 10 22. Good luck.