I bought one of the 9mm AR uppers as well as the mag well adapter,bcg,and buffers from PSA. Had some problems with rounds jamming so PSA replaced the bolt. Next problem was the mag adapter moving around in the mag well. PSA replaced the adapter with an even worse one. Rather than going back and forth with PSA I decided to fix it myself. I had to file the front of the adapter flush with the mag well and drill and tap for a set screw to hold the adapter tight in the mag well. Took it to the range today and it works great. Hopefully the problem is solved.I ran about 100 rounds through it with only two jams and that was with some cheap remanufactured ammo. No problems with the good stuff. PSA customer service was great but I think this product has issues; especially the mag adapter. Lots of fun shooter now that it's working!