The Colt 9mm SMG is a closed bolt, blowback operated SMG, rather than the conventional direct impingement gas operation of the standard 5.56x45mm M16 type rifle. The overall aesthetics are identical to most M16 type rifles. Changes include a large plastic brass deflector mounted toward the rear of the ejection port. Factory Colt 9mm SMGs are equipped with a 10.5 inch length barrel and have an M16 style upper receiver, which means they feature a fixed carry handle, no forward assist and A1 sights (with 50 and 100 meter settings). The magazine well of the receiver is modified using a special adaptor to allow the usage of smaller 9mm magazines. The magazines themselves are a copy of the Israeli UZI SMG magazine, modified to fit the Colt and lock the bolt back after the last shot.