Colt Expanse M4 carbine puts a Colt quality AR-15 within easy reach of the modern Armshop 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. Either way, the Expanse™ M4 in 5.56 x 45 NATO (.223 Rem.) is a great way to add another Colt to the stable. The Expanse™ can be upgraded with the addition of a forward assist and dust cover.