M4

M4 is a designation used for several unrelated systems and vehicles. In military use, it most often refers to the M4 carbine, a compact 5.56×45mm NATO assault carbine derived from the AR-15/M16 family; in civil and infrastructure contexts, the M4 refers to the M4 motorway in the United Kingdom; and in historical armored fleets, it refers to the M4 Sherman tank used by the Allies in World War II.

M4 carbine: The M4 is a lightweight, air-cooled, gas-operated carbine with a 14.5-inch barrel, standard-issue collapsible stock, and accessory rails for optics and grips. It fires 5.56×45mm NATO cartridges and uses detachable STANAG magazines. The M4A1 variant has fully automatic fire; the M4 family supports a variety of attachments and is widely used by the U.S. forces and many allied militaries.

M4 motorway: The M4 is a major east–west motorway in the United Kingdom connecting the London area with southwest Wales. It passes through southern England and South Wales, including Berkshire, Wiltshire, and Bristol, and connects with the Second Severn Crossing to link the English and Welsh motorway networks.

M4 Sherman: The M4 Sherman is a U.S. medium tank produced during World War II. Named after General William Tecumseh Sherman, it entered service in 1942 and became the main U.S. Army and Allied medium tank. It was produced in many variants, including M4, M4A1, M4A3, and M4A6, with armament evolving from a 75 mm gun to 76 mm in some models.