I have an old Marlin .22 rifle I just fixed up and had a chance to finally shoot it last Sunday. It has standard open sights. At 10 yards, it is consistantly shooting to the right of my aiming point 1-1 1/2 ". So, as I will have to drift my front sight to the right, is there any approximate amount one should drift it over, or is it just a move the sight and shoot, move the sight and shoot type of thing till I am happy? Thanks.