I have had some new barrels change tune after they get broken in. Usually all that is needed is one turn of the tuner. I have had barrels (including my current one) that has shot best with some weight added. I try to use as little weight as necessary. I currently have 1 1/2 oz. added to my standard weight Harrel tuner. If you aren't happy with the tune with the standard tuner, adding weight is worth a try. Once the barrel is broken in, and you have found the true sweet spot, it should stay in tune. Make sure you are using known good ammo to tune cause you can't tune out the flyers from bad ammo.