The M4 Carbine is a lightweight, gas-operated, air-cooled, selective-fire weapon chambered for 5.56×45mm NATO ammunition. It is the shorter and lighter variant of the M16 rifle, and has become one of the most widely used firearms by the United States military and its allies.

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The M4 Carbine was originally developed in the early 1990s by the United States Army's Armament Research, Development and Engineering Center (ARDEC) in response to the need for a more compact and versatile weapon for close quarters combat (CQC). The M4 was designed to replace the M3 submachine gun and complement the M16A2 rifle in infantry units. The goal was to create a weapon that was easy to handle, lightweight, and had the same level of accuracy and lethality as the M16. The M4 Carbine was based on the M16A2 rifle, but with several modifications. It has a shorter barrel length of 14.5 inches (37 cm) instead of 20 inches (51 cm), and a collapsible buttstock that can be adjusted to fit the individual user. The M4 utilizes a 30 round detachable box magazine or other STANAG magazines.

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Over the years, the M4 Carbine has undergone several upgrades and modifications. In 2013, the U.S. Army began a program to replace the M4 with a new carbine, but the program was eventually cancelled due to budget constraints. Instead, the Army opted to upgrade the M4 with new components and accessories, such as the M-LOK handguard and improved iron sights. The M4 Carbine has seen extensive use in a number of conflicts, including the wars in Iraq and Afghanistan. It has proven to be a reliable and effective weapon.

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This particular firearm is a surplus firearm that was used by United States law enforcement agencies for drug enforcement units.