Just the shooting will burnish the barrel. The bullet will do a tiny bit of polishing with every shot.
Let me ask this and I will add Im not asking to argue but to get what you all think .
If we are looking to burnish the barrel evenly . I would think you would need to remove all foriegn materials out of the bore before each shot . If copper biulds up in the bore the bullet is running on it and not the bore it self . This to me would give a bore uneven burnishing . After 100 rounds or so when you cleean all the copper fouling from the bore those parts of the bore that were under that fouling will have had no burnishing . That to me would not be a good and quick way to get your rifle shooting it's best . Sure it will get done sooner or later but why not get it done in 20 rounds rather then 200 .
EDIT : Thats funny eldermike we were thinking and posting the same thing at the same time