Law Enforcement Only Colt M4 Commando is the most compact of the Colt 5.56mm Family of Weapons featuring a 4-position sliding buttstock and an 11.5" (29.2 cm) long barrel. The M4 Commando is famous for its lightweight, ease of handling, accuracy and reliability, qualities that make it a valid choice for a wide variety of law enforcement applications. In fact, the Colt M4 Commando is often chosen over smaller, less powerful sub-machine guns, allowing for full 5.56mm power and accuracy, in a sub-machine gun size weapon.