This Brownells’ exclusive Complete AR Upper Receiver is Made in the USA. Chambered in 300 Blackout and featuring a 16” barrel with a 1:8 twist. The standard A3 13-slot aluminum flat top receiver comes with a 10” handguard utilizing the KeyMod rail system. A low profile gas block, bolt carrier group, charging handle, forward assist, ejection port cover and phosphate finish help to complete this outstanding package. This complete A3 upper receiver will attach to almost any standard AR-15 lower receiver.