I'd do what Brad was suggesting, I've done it on several rifles and it's the way to go.
Emery or corundum or whatever the black abrasive in valve grinding compound is is extremely brittle and crushes finer and finer under pressure. It never "wears out", just crushes to such a fine grit in short order that it's polishing more than cutting. This is a good thing because the embedded, soft bullets will cut more at the breech end where the grit is fresh and large, and once past the tight spots the soft lead won't expand much and so won't really remove any metal at the muzzle end until you're nearly done. As you lap, the grit will remove the bluing from the interior of the barrel and that wear will progress toward the muzzle end. What you should watch for very closely is bare metal at the muzzle end as the wear progresses......When you start to see the bluing getting thin within an inch or two of the muzzle, it's time to STOP.
Embed your soft lapping bullets by rolling between two steel plates coated with abrasive paste. Be careful not to make the bands smaller than groove dimension. A grain or two of Dacron, fluffed up between bullet base and powder, will help seal gas behind the bullet when using a very light charge of powder and will help squeegee the bore after every shot so you don't have to patch out but every 3-5 rounds. You may want to clean the chamber EVERY round if you're getting any grit blown in there. Using fired brass, only resized on the very front, just enough to hold the bullet while you chamber it, will minimize grit blowing back into the chamber. The cases you use for fireforming will be trash when you're done, so if you have some old stuff laying around or some mixed range pickups this is the time to use them.
