Couple thoughts on the subject..
Setting back a Factory barrels brings several thoughts to my mind.
1. Factory barrels are generally lessor quality barrels than what is available in the aftermarket. Why spent $200-$400 to set back a marginal barrel quality barrel.
2. Is there ennought metal to do the setback safely? You will have to rebed the stock as the contour will be moved back.
3. Indexing the writing on the barrel may or may not be a concern to you.
4. Is the slight increase in powder capacity and the sharper shoulder angle going to give you the velocity or accuracy gain you are looking for?
5. Are you looking for more horse power then why not go to a 6mm/.284?
Don't forget barrel life decreases exponentially as velocity and preasure increase. Speed does not always equal accuracy.