Colt's Expanse M4 carbine puts a Colt quality AR-15 within easy reach of the modern sportsman looking to enhance his or her collection, or the first-time buyer looking for a starting point on which to build their dream modern sporting rifle. The Expanse M4 in 5.56 NATO/223 Rem is a great way to add another Colt to the stable. It's built at the Colt Competition Rifle facility with the same Colt parts, steel, and forged aluminum as the rest of the M4 line. This model's complete upper receiver includes the forward assist and dust cover.