page_title: Rheinmetall Rh-120
section_title: Background
hierarchical_section_title: Rheinmetall Rh-120 / Background
caption_attribution_description: Leopard 2 Prototype No. 19 on Bridge M 80
context_page_description: The Rheinmetall Rh-120 is a 120 mm smoothbore tank gun designed and produced by the West German Rheinmetall-DeTec AG company, developed in response to Soviet advances in armor technology and development of new armored threats. Production began in 1974, with the first version of the gun, known as the L/44 as it was 44 calibers long, used on the German Leopard 2 tank and soon produced under license for the American M1A1 Abrams and other tanks. The 120-millimeter gun has a length of 5.28 meters, and the gun system weighs approximately 3,317 kilograms.
  By 1990, the L/44 was not considered powerful enough to deal with future Soviet armour, which stimulated an effort by Rheinmetall to develop a better main armament. This first involved a 140-millimeter tank gun named Neue Panzerkanone 140, but later turned into a compromise which led to the development of an advanced 120 mm gun, the L/55, based on the same internal geometry as the L/44 and installed in the same breech and mount. The L/55 is 1.32 meters longer, giving increased muzzle velocity to ammunition fired through it. As the L/55 retains the same barrel geometry, it can fire the same ammunition as the L/44.
context_section_description: Because of concerns about the inability of the 105-millimeter (4.1 in) L7 tank gun then in use across NATO forces to penetrate new Soviet armor, as proved in German tests on four T-62 Soviet tanks captured by Israel following the June 1967 Six-Day War, Rheinmetall was paid for the development of a new tank gun. A project started in 1965, as the Bundeswehr felt a more powerful gun was needed for its new tanks. The first instance of a larger Soviet tank gun was witnessed on the chassis of a modified T-55 in 1961. In 1965, the Soviet Union's T-62 made its first public appearance, armed with a 115-millimeter (4.5 in) smoothbore tank gun. The Soviet decision to increase the power of its tank's main armament had come when, in the early 1960s, an Iranian tank commander defected over the Soviet border in a brand-new M60 Patton tank, which was armed with the 105-millimeter (4.1 in) M68 gun, the US version of the British Royal Ordnance L7. Despite the introduction of the T-62, in 1969 their T-64 tank was rearmed with a new 125-millimeter (4.9 in) tank gun, while in 1972 Nizhny Tagil began production of the T-72 tank, also armed with the 125-millimeter (4.9 in) gun. At the fighting at Sultan Yakoub, during the 1982 Lebanon War, the Israeli government claimed to have destroyed nine Syrian T-72s with the Merkava main battle tank, armed with an Israeli version of the American M68 105-millimeter (4.1 in) tank gun. Whether true or not, the Soviets test-fired a number of Israeli M111 Hetz armor-piercing discarding sabot rounds at Kubinka, finding the 105-millimeter (4.1 in) round was able to perforate the sloped front section plate but not the turret armor of the T-72 tank. In response, the Soviets developed the T-72M1. This led Israel to opt for a 120 mm tank gun during the development process of the Merkava III main battle tank. This case is similar to the American decision to replace the M68 105-millimeter (4.1 in) tank gun with Rheinmetall's 120 mm gun in 1976; the introduction of the T-64A had raised the question within the armor community whether the new ammunition for the existing gun caliber could effectively deal with the new Soviet tank.
  In 1963, Germany and the United States had already embarked on a joint tank program, known as the MBT-70. The new tank carried a three-man crew, with the driver in the turret, an automatic loader for the main gun, a 20-millimeter (0.79 in) autocannon as secondary armament, an active hydropneumatic suspension and spaced armour on the glacis plate and the front turret. The new tank concept also had improved armament, a 152-millimeter (6.0 in) missile-launching main gun, designed to fire the MGM-51 Shillelagh anti-tank missile. However, the German Army was interested in a tank gun which could fire conventional ammunition. Although there were attempts to modify the 152-millimeter (6.0 in) tank gun to do so, the process proved extremely difficult, and the Germans began development of the future Rheinmetall 120 mm gun instead.
  In 1967, the German Ministry of Defense decided to re-open a Leopard 1 improvement program, known as the Vergoldeter Leopard ("Gilded Leopard"), later renamed the Keiler ("Wild Boar"). Krauss-Maffei was chosen as the contractor, and two prototypes were developed in 1969 and 1970. This program grew into the Leopard 2; the first prototype of the new tank was delivered in 1972, equipped with a 105-millimeter (4.1 in) smoothbore main gun. Between 1972 and 1975, a total of 17 prototypes were developed. The new 120 mm gun's ten-year development effort, which had begun in 1964, ended in 1974. Ten of the 17 turrets built were equipped with the 105 mm smoothbore gun, and the other seven were equipped with the larger 120 mm gun. Another program aimed to mount the 152-millimeter (6.0 in) missile-gun was also developed in an attempt to save components from the MBT-70, but in 1971 the program was ended for economic reasons. Instead, the Germans opted for Rheinmetall's 120 mm L/44 smoothbore tank gun.
caption: Prototype of the Leopard 2
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