IMHO barrel "break in" is a thing of the past. Just sight the rifle in and find the ammo the gives you the best groups. I've never had a rifle in over 30 years that couldn't deliver a 1" group or less with factory ammo and have never followed a break in procedure.
The last two being both Remingtons 700's one in a 7mag dbm and the other a 22.250 vs ,both deliver 1/8" groups with Ferderal 140 tbbc and horandy custom 139's and hornady 55gr moly v max.