Received this upper a little more than a week ago. Out of the box I was impressed by the look and feel of the upper. I took it to the range and ran about 150 rounds through it. Once I got it dialed in I'm making sub MOA groups at 100 yards. Love the gun but the Customer service from Atheris is second to none. This is a small company with a great product and outstanding customer service. Give it a try, you won't be disappointed!