I haven't seen any mention of a bipod, or other shooting aid for a rest.

There are several options, pick one you like and, after you finish sighting in the rifle off the bench, never shoot off the bench again. Only shoot using your chosen field rest/bipod/sticks, whatever. Note that you will most likely have to adjust your scope a little as bench to bipod will usually move the zero a little.

Generally accepted wisdom for accuracy potential of a rifle is a 1 MOA rifle out to 500yards is adequate, and a 1/2MOA rifle is needed to shoot further out. It doesn't sound like you need to do anything to your rifle except work up a load.

Jeremy

You can't swing a dead cat in a gun-store without knocking over several 500 yard hunting rifles. If you're really going to put your limit at 500 yards I wouldn't even bother with turret scopes.

There's an old target shooters saying that goes something like this.

Beginners talk about guns.
Experts talk about ammo.
Winners talk about wind.