The Colt M4 is a lightweight, air-cooled, gas-operated carbine that is widely used by military and law enforcement agencies. It features a 5.56x45mm NATO caliber and is known for its modular design, allowing for various attachments and accessories. The M4 has a maximum effective range of about 500 meters and can be configured for semi-automatic or fully automatic fire. Originally developed in the 1990s, the M4 is an evolution of the earlier M16 rifle. It has become a standard issue firearm for the U.S. Army and is favored for its versatility and reliability in various combat situations.