I’ve yet to see or have explained to me how a small axial misalignment or being slightly nonconcentric for that matter makes a nickels worth of difference in a radial cut such as truing an action face or bolt face. Unless there’s something wrong with the lathe, the result is going to be perpendicular to the axis. If one is going to after the threads, then yes by all means a spider is a nice way to go as long as it’s not some garbage piece of aluminum sticking a foot out of a four jaw. I’ve machined a collar to fit the outside of the action, trued between centers on a precision mandrel passing through the action and then transferred to the chuck, indicated on the mandrel, removed mandrel, and cut the threads. Don’t like doing it that way, tedious and generally a waste of time. If you go after the lugs chances are your action will be making a trip to Dan to put the bolt handle back where it belongs or it won’t extract right😄.
Money is better spent on a custom action, and a good barrel, the latter being the most important part of the puzzle. If a gunsmith actually charged the amount of time it takes to fully blueprint one at a rate a machine shop charges, it would cost $$$$.
Feel free to straighten me out😄
Are you assuming your chuck jaws hold the outside of an action so that the bore is true to the spindle axis? LOL. Do you have much machining experience?
