Grey Ghost Precision is now offering their own stripped AR-15 lower receiver. The cleverly named Cornerstone lower is a forged lower that is built to the same level of detail and tolerances as the billet lowers used on their Specter line of rifles. The lower is machined for a forging by Mega Arms to tighter than mil-spec tolerances.
It has everything you expect from a quality lower like 7075-T6 aluminum construction and a hard anodized finish. It also has some features that go over and above like pictogram selector markings, a nylon-tipped upper to lower fit tensioning screw, and a flared magazine well.