Has anyone had this done? I understand that it makes things tighter, but I don't understand how it can help accuracy. Can anyone explain it to me, or tell me who can do it in the Austin area (Savage SA)
Every manufactured item has built in tolerances. Front receiver ring may be slightly uneven, one lug recess may be a bit of from another, etc. "Blueprinting" tends to tighten up the tolerances.
It may or may not help much, depending on your particular rifle.
Truing an action basically means that all tolerances between interlocking and mating surfaces of the bolt and receiver are reduced (tighter, as you stated) as much as possible by lapping, honing, etc., and aligns the bolt dead-center with the chamber. One of the biggest advantages, in terms of accuracy, is that it takes any "play" out of the bolt, reducing vibration upon firing. On the other hand, you really don't realize the full benefits of action truing with factory ammunition.