New barrels have tooling marks in the bore and a break-in is required to get the smoothest possible bore for accuracy sake. Granted, this is a production barrel and may not have the tighter tolerances of a match barrel, but a break-in is really the way to go.
Like what was said, clean the bore after every 5 rounds until 50, then after every 10 rounds until 100. Use Sweets 7.62 to get every bit of copper fowling from the grooves/lands until the patch pushed through the bore comes out completely clean.
And of course I assume you know to NEVER clean a rifle bore from the muzzle end but rather from the chamber end. Some rifles like the M1 and M1A you cannot do this, and there are guides offered for these rifles to minimize any damage to the crown. If you ding the crown during cleaning, it can cause accuracy to fall off.
This product has worked great when I broke-in my match barrel on my competition AR.
308 FF Ammo - DTAC - FINAL FINISH by Superior Shooting Systems