Re: Remington 700 SF II 300RUM
Perhaps Nothing. Have you seen what it will do out of the box for accuracy? You may find that it does just fine with no adjustments needed. There are the standard things that you can do to help with accuracy, however most need the help of a smith.
First thing you can do is break it in properly if you haven't already. Other things that you can have a smith do are:
True the Bolt Face
Custom Recoil Lug
Re-Crown the Muzzle
Bed Action in the Stock
Jewell Trigger (May do this one yourself)
Re chamber for your caliber to clean up any sloppy factory work
Before doing any work on your barrel however, I would have a smith with a good borescope take a look and see if the original barrel is worth the work. It may not be. It is worth knowing before hand so you know what you are dealing with.
If you always do what you've always done, you will always get what you've always got.