What Is Action Truing?

[jayhawker]

Could someone tell me what exactly is done to a rifle when it's sent to the gunsmith to get "the action trued" and/or having it "accurized?

[Blue Avenger]

truing is just getting every thing square and parallel. touching surfaces meet fully with equal contact pressure

[darkker]

You lose a few hundred frog skins... It can mean several different things.
On non-nut guns, the assumption is that the shoulder of the receiver, where the barrel is threaded; is not true to the barrel.
If you square it off, then the lock-up of the barrel is more secure, and relieves stress, improves harmonics... Also they tend to "square-off" the locking lugs-to-receiver mating surfaces.
The other common thing is to polish the cocking ramp/parts of the bolt. Thereby syncronizing the position of the bolt handle, and cocking of the firing pin. It has been my experience that this is mostly done to "smooth" the cocking action of the bolt handle.

The part about the locking lugs of the bolt is unnecessary, due to the whole floating bolt head of Savages.