from what iv read in a few minutes they make cheap lowers and well complete guns, but are a ok or some said very good quality. Im guessing he bought the stripped lower and had the trigger job done and put the bcm upper on it. Im now alittle worried, my guess is he bought it this way or had it built. I guess worst guess is a swap out the guts of the lower, but im betting its good to go. I cant get a scope or sights for week or so till I get back from indiana, so gonna be a fun wait. lmao imma bet my self if I bought a janked up ar knowing what I know and not shooting it before hand. my fault though, just like him not driving the truck that had 350000 miles on it, so I figure rebuild the lower is better then the day that engine went plus I had no use for the truck any more