So, let's say you have a Savage barrel with the nut. Let's say you set the nut and headspace BUT you put red Loctite or similar adhesive on the nut.

Add an index mark on the bottom of the action, and mark the nut to the index mark.

Then you could remove the barrel after the adhesive set and the nut now is the shoulder.

No need to re-headspace the barrel next time. Just tighten to the index mark. Done. Just like a standard shouldered barrel.