United States Department of Defense - M113 Armored Personnel Carrier

The M113 is an armored personnel carrier family of vehicles in use with the US military and many other nations.

It is a fully tracked vehicle capable of limited amphibious operation in lakes and streams, extended cross-country travel over rough terrain, and high speed operation on improved roads. The M113 family has many variants and modifications that are used in a variety of combat and combat support roles. Approximately 80,000 units of all types have been produced worldwide making it the most widely used armored fighting vehicle of all time. Although not a tank, or even designed as a fighting vehicle, the M113 was the most utilized armored vehicle of the Vietnam War. It inspired newer generations of more heavily armored and armed infantry fighting vehicles. Yet it remains in front-line service and production in the 21st century, and the M113 was recently declared the best in a television comparison of "top 10" armored personnel carriers and infantry fighting vehicles.
Weapons

The basic M113 armored personnel carrier can itself be fitted with a number of weapon systems. Most common is a single .50 caliber M2 machine gun or 40mm Mk 19 automatic grenade launcher. A number of anti-tank weapons were also fitted. Armored Cavalry units in Vietnam removed jeep mounted M40 106mm recoilless rifles fitting them to their M113s instead. The US Army also developed a kit that allowed the Dragon anti-tank missile system to be mounted to the existing machine gun mount, without having to remove the machine gun. This allowed the commander to use the weapon, as well as the machine gun.