I have just had a Sako rebarreled to 6mm-223. I've tried 3 different projectiles and 4 different powders so far and they all give 1.5 to 2 inch groups. The smith wasn't concerned and said that chrome moly barrels can take up to 200 rounds to wear in. That doesn't sound right to me, what do you think? In my experience, if they dont shoot reasonably well with everthing then it wont shoot exceptionally well with anything. The barrel is a Shilen 1-10 twist, 20 inch long medium varmint.