I have a Rock River Arms National Match A4 upper in excellent condition for sale. The upper has a stainless steel Wilson air gauged 20 inch heavy match barrel 1X8 twist with 223 Wylde chamber. It has a rifle length gas tube, national match barrel sleeve, detachable national match carry handle, .040 black front post and 1/4 min by 1/4 min adjustable hooded national match rear aperture sight. The barrel has been subjected to a a break-in process and has had very few rounds fired through it. With match quality ammunition in the hands of a skilled marksman it is capable of producing 1/2 MOA groups at 100 yards. When mated with a Rock River National Match lower it is guaranteed to achieve 3/4 MOA. Please feel free to contact me with questions or to request additional photos.