Re: New AR breakin
Clean the chamber before and after shooting the rifle.
Clean and with grease lubricate the bolt carrier group before and after shooting the rifle.
While you're at it, pull a snake with Kroil applied to the first few inches through the bore, chamber to muzzle, straight out, before and after shooting the rifle.
Before firing, with a chamber rod and cloth-wrapped brush, snake, and organic de-greaser, remove oil from the chamber and bore remaining since cleaning.
If this isn't done right, don't do any of it. Really. Just shoot the rifle, but your rifle WILL malfunction, your rifle WILL be unreliable, your rifle WILL wear out sooner, so learn how to do it right.
A good reference is
www.zediker.com. Cleaning and Maintenance.