Quote Originally Posted by darkker View Post
.... Are you implying that the barrel nut not being square can somehow, pull the barrel sideways in the receiver? But won't need the threads or bore then fixed, if you buy a squared nut??

If the customer needs a bunch of windage to get his scope on, either the scope mounts are drilled out of alignment, or the rings are off. If it was the barrel pulled out of alignment from the receiver, you now have a stretched receiver bore. A squared nut doesn't fix that.
I'm not Jim but even if the barrel nut face was .020" off of perpendicular to an axis drawn through the center of the nut it would not generate enough force to stretch or otherwise damage the heat treated receiver ring.
Such a deviation from perpendicular would however set up uneven tension and stresses which would affect the vibration pattern of the barrel with potential adverse consequences for accuracy.
Ideally you want everything making up the barrel/receiver ring/barrel nut interface to be as perfect as possible so as to set up even pressure 360* around the barrel. This will allow the barrel to vibrate (whip) at it's natural frequency without any influence from the nut.