My "opinion" is the only breaking in of a good custom lapped barrel is the throat. To alleviate this I put a bronze brush in my electric drill, wrap the brush with a little 0000 steel wool and lap the chambering fluff out of the throat. About 5-10 seconds. The bore has been lapped already and the machining fluff from the reamer in the throat is your problem. Now, just go out and shoot it. I don't use factory barrels and would not form any opinion on them.
