I'm with Bart on this one.
The best thing you can do is square the face of the receiver with the internal threads.
It's rather easy. Brownell sells action facing mandrels pretty reasonable.
They are easy to use. Get one for the thread pattern of your action. Screw on the action, and stick it in the lathe between centers. Use a dial indicator to make sure everything is lined up.
Take some lay out ink and coat the front of the action and shave it just to the point you remove the layout ink.