Good morning . I have an upper receiver on a 300 BLK with a forge mark that is a capital U . I understand that it is a firm that is Unifor / Brawo . which is an American forging company . I know the forge markings are just who forged the upper and ships to manufactured who finish and mark them with their company logos . It came on a supposed factory Aero Precision assembled lower with Aero Precision marked lower . Fit / finish are as good as my BCM and others I have . I know typically Aero uses the A on their uppers , but have seen on some of the forums that they have used them in the past and that Spikes had used them occasionally . Great gun , no problems , just wondering if anybody else had seen them or know anything about them .Thank you . Have a great weekend .