I have 3 of their uppers. 20" chrome lined A2 rifle upper, 11.5" 7.62x39 upper, 11.5" chrome lined 5.56 upper. All run flawless except: The 20" A2 upper doesn't like factory steel case ammo...empties can stick in chamber. Note: My steel cased reloads do function fine in the 20" A2 upper. I'm happy with them. I bought the uppers complete with bolt carrier group and charging handle. I later converted the 11.5" 5.56 upper to a gas piston operation, and it's still running fine...it's mainly used for full auto firing.