The 120mm ammunition system equips the MlA1 Abrams tank. It consists of a family of kinetic energy (KE) rounds and a family of high explosive anti-tank (HEAT) rounds. The KE rounds use a high length over diameter ratio subcaliber projectile with a depleted uranium (DU) fin-stabilized rod as the penetrator element. Traveling at supersonic speed, this penetrator concentrates an extremely high level of kinetic energy over a relatively small surface area of the target. The high specific energy on target enables the KE round to penetrate even the most resistive armor plates. The HEAT rounds, on the other hand, take a shaped charge warhead to targets. This shaped charge warhead, with its inherent blast and fragmentation capability, also provides additional weapon defeat capability. All 120mm rounds use a common combustible case which structurally combines the ammunition's components prior to firing and is completely consumed during firing. The combustible case is the primary reason for the superior interior ballistics performance of the 120mm ammunition. This breakthrough in cannon ammunition technology allows both a greater chamber volume for the propellant and a higher working chamber pressure, thus giving the rounds greater muzzle velocities and higher ballistic efficiencies. The combustible case also minimizes round weight and, because the metal base is the only element ejected, the armount of spent cartridge case material and propellant gas within the tank is greatly reduced.
The M120 120mm Mortar replaces the M30 4.2 Inch Mortar in motorized infantry units. The M120 is transported on the M1100 Trailer by the M998 High Mobility Multi-Wheeled Vehicle (HMMWV). The M120, like all other US mortars, fires fin-stabilized ammunition from a smooth bore. Although heavy mortars require trucks or tracked mortar carriers to move them, they are still much lighter than field artillery pieces. They outrange light and medium mortars, and their explosive power is much greater.