A barrel nut will allow for more consistent setting of headspace. False. Really, How so? how is something that moves ever going to be more consistent than a solid chunk of steel that can’t move?
All these folks that blather on about "but muh tolerances!!!".
A tolerance is an acceptable deviation from the spec'd nominal dimensions, that deviation is set by the manufacterer. True.
A barrel, equipped with a barrel nut will allow you to compensate for those deviations from nominal. So? Here you are agreeing with my first statement. A good action won’t have deviations. Barrel nuts are for those that do.
What is the tolerance (deviation from nominal)of the manufactured action? What is the tolerance (deviation from nominal) of the shouldered prefit? Most are +/-.0005 - +/- .001" Prove it with evidence. Measure your good action yourself. Compare to print. Find me an example of a good action that gets released from the manufacturer that isn’t.
While you most likely won't run into excessive headspace, tolerance stacking says SOME will have too much headspace for maximum accuracy potential. Prove it with evidence. Why? the fact that you have, in your previous statment admitted there are tolerances in play, is proof enough that some headspace, while not excessive, will be more than most that are interested in accuracy, would find desireable. If you have a shoulder and a good action then you don’t have to worry about it at all.
The way around that? Not needed. For you, maybe. It’s not if you action is good.
Either have a gunsmith install and properly headspace the barrel, or use a barrel nut system, which (if chambered correctly) eliminates the issue. No need for either in the current era of manufacturing. Because no one has ever shipped a product that is on the edge of specs. If the spec is a thou, like a good action is these days, and the smith is worth a shit and can hit a spec then it has kk need these days.