Elevate your firearm performance with the impeccable engineering of this 5.7x28mm Complete Upper.This cutting-edge AR57 Upper seamlessly integrates into any standard lower ensuring you experience smooth hassle-free installation and use.Delving into the specifics the unit boasts a robust Kryptonite Monobloc construction derived from a single block of Aircraft Grade 7075 T6 aluminum rated at a remarkable 83000 PSI strength. The precision milling guarantees accuracy to within .002 tolerance.The barrel spanning 12 inches concludes with a perforated muzzle brake attached via 1/2 x 28 threads culminating in an overall length of 18 inches making this a suitable complete upper receiver for your AR Pistol. 5.7x28mm Complete Upper 12" - AR57Aircraft Grade 7075 T6 aluminumMelanite-treated metal componentsChambered in 5.7 x 28 mmFurther enhancing its versatility the upper incorporates a 13-slot Picatinny rail augmented by 3-slot upper and lower forward rails.Durability remains paramount with all key metal parts undergoing melanite treatment. Eliminate the concerns of a gas system clogging as this design champions a chamber that resists carbon and fouling accumulation even through prolonged shooting sessions.Celebrate the genius of simplicity with its free sliding bolt the sole moving component and revel in effortless maintenance.Lastly the AR-57 system's unique design ensures that spent rounds are ejected through the lower's magazine well.Order your new AR-15 5.7x28mm upper receiver online today!Looking for AR15 Parts? Find great deals on all in-stock AR-15 Rifle Parts available now from the brands you know and trust!*Caution : Must install buffer before use