I recently built an AR-15 with my dad, using a PSA lower. After completing the lower, we spent some time shopping around kfor an upper, and decided on the PSA carbine length 16" upper. After ordering, we got the email confirmation for shipping, and not but a day later got a phone call from PSA. Apparently, they had a computer glich that caused them to show they stocked the carbine length, when they were actually sold out. So, they gave us a free upgrade to mid-length as compensation for their error! Now for the quality: The M4 feedramps are beautiful. The same quality or better than I've seen in pictures of much higher dollar ARs. The gas key bolts are properly staked. The fit and finish are excellent. So in summation, if you are considering PSA, I don't think you can go wrong. Between exceptional quality and great customer service, PSA is headed the right direction.