PTAC 16" Carbine Length 5.56 NATO 1/7 M4 Nitride Upper - w/ BCG & Charging Handle - 45240
Product Review (submitted on September 22, 2016):
I have two of these uppers, the most accurate I own, 100% reliable. One has over 1500 rounds of the cheapest ammo I can buy, it runs like a sewing machine.
At some point these will increase in price, buy cheap and stack deep.