This 20″ bull barrel complete upper receiver assembly is the perfect choice for precision shooting. The fluted bull barrel profile provides adds strength for stability reducing recoil and increasing accuracy. The barrel is made of high-quality stainless steel providing durability and longevity. The 1-9 twist rate is suitable for stabilizing heavy projectiles. This is an excellent option for shooters who want a heavy barrel with precision shooting in mind. Starts with the 20″ .223 caliber fluted bull barrel made from 416 SST with a 1-9 twist mated to the A3 Flattop receiver which includes the bolt carrier charging handle forward assist and ejection port cover. The upper is then topped off with the lo-profile gas system and the ergonomic 15″ Palm Handguard® with M-LOK slots and a Picatinny top-rail.