I agree with Texasbygod. I have found that light reflection of one side of the front sight can cause you to shoot off by that much. Try either smoking or sight blacking the right side of the sight and see if it makes a difference. If it does, a more permanent cure can be had by painting the right side of the front sight with a clear dullecoat paint from you local hobby shop and it doesn't permanently alter the firearm in any way.