Recently bought a complete PSA AR-15 lower and PTAC upper and once together, discovered they didn't fit well, which was surprising because my last PSA/PTAC combo fit and worked beautifully. I called PSA customer service, they asked me to send both parts back, which I did, and told me they were backed up and would at least 15 days until they even looked at them. Well, TODAY is day 15 since they received the receivers and my repaired AR was delivered to my door today !! It looks like they replaced my complete upper receiver and even threw in a spare part or two for free !! EXCELLENT customer service, everything now fits and operates beautifully and I really appreciate the extra parts they included. PSA customer service gets a big thumbs up !!