Centre punch, I didn't finish answering your post before leaving the house this AM. I call it the Gre-Tan method, only because he sells most of the tooling. (in a nutshell)I reamed the bolt raceway and then using a special jig, the action is mounted and centered perfectly in the lathe so it is spinning on the axis of the bolt raceway. http://www.gtrtooling.com/prod05.htm
Then all the thread and bearing surfaces are recut using a single point cutter. The factory bolt is also replaced with a custom bolt ground to tighter tolerances. This give you the best possible concentricity and accuracy from a remington action. I know this isn't a very detailed description, but it is close.