Ok so I understand the benefit of a concentric neck and turning necks to get this. My question comes to the chamber the round will go in. Most of the neck turning I see is for rifles with a chamber cut that has a tighter neck than that of factory brass and as such the brass needs turned to fit. If I am using a chamber on a factory barrel that isn't a tight neck do you still want to turn necks? I had heard you only want .001-.002 clearance between the neck and the chamber wall. Is it better to have a concentric neck or to have one that fits closer to the chamber wall? Do you want to just touch them up until the hit concentric and then stop or do nothing to them at all? I am looking for a little more accuracy now and thought this would be the next easy spot to look.