Redbone when an action is "blueprinted" or "trued" the internal surfaces; threads, lugs, lug seats, bolt face, and reciever face, are all cut perpendicular or parralel to the bolt raceway. When properly done and fitted with a new barrel, everything should be in near perfect axial alignment. Thus accuracy should be excellent.
When an action is said to be "squarred", many times this just means the reciever face was squared up to the existing action threads, and the other operations were left out.
This operation alone may improve the fit of barrel to action, if a problem existed. This is what most smiths would do if you just requested a new barrel be fit to your action.
If you want a action blueprinted be specific in the operations you want done, or you may end up with a bored raceway and a sleaved bolt which will tighten up a remy but will also add to the cost.
hope this helped.
