Rheinmetall Rh-120

The development of the 120 mm L/44 gun 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 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 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 tank 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 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 round was able to perforate the sloped front section plate but not the turret armour 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 tank gun with Rheinmetall's 120 mm gun in 1976; the introduction of the T-64A had raised the question within the armour community of whether the new ammunition for the existing gun calibre could effectively defeat 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 crew of three, with the driver in the turret, an automatic loader for the main gun, a autocannon as secondary armament, an active hydropneumatic suspension and spaced armour on the glacis plate and front turret. The new tank concept also had improved armament, a 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 tank gun to do so, the process proved extremely difficult, and the Germans began development of the future Rheinmetall 120 mm gun instead. , firing its US-built M256 120 mm tank gun In 1967, the German ministry of defence 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 smoothbore main gun. Between 1972 and 1975, a total of 17 prototypes were developed. The new 120 mm gun's ten-year development effort ended in 1974. Another program aimed to mount the missile-gun was also begun 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. ==Design features==

Rheinmetall's L/44 tank gun has a calibre of 120 mm, a length of 44 calibres (), and a chamber volume of 10.2 liters (622.44 in3). The gun's barrel weighs , and on the M1 Abrams the gun mount weighs , while the new barrel (L/55) is 55 calibres long, longer. The bore evacuator and the gun's thermal sleeve, designed to regulate the temperature of the barrel, are made of glass-reinforced plastic, while the barrel has a chrome lining to increase barrel life. but with recent advances in propellant technology, the average life has increased even further. The gun's recoil mechanism is composed of two hydraulic retarders and a hydropneumatic assembly. ==Variants==

Rh-120 L/44 120mm Production of the German Leopard 2 and the new 120 mm tank gun began in 1979, fulfilling an order for the German Army. The L/44 Extreme Service Condition Pressure (ESCP) is , the Permissible Maximum Pressure (PMP) , and the Design Pressure from . Although the American M1 Abrams was originally armed with the M68A1 105 mm gun (a version of the L7), the United States Army had planned to fit the tank with a larger main gun at a later date, and the tank's turret had been designed to accommodate a larger 120 mm gun. The gun, known as the M256, was based on the L/44 tank gun, although manufactured at Watervliet Arsenal. Tanks armed with versions of Rheinmetall's gun produced under licence include Japan's Type 90 and South Korea's K1A1. The M256 based on the L/44 when firing M829A1 Armor Piercing, Fin Stabilized, Discarding Sabot - Tracer (APFSDS-T) ammunition can attain a Peak Chamber Pressure of at and at . Rh-120 L/55 120mm of the German Army with 120 mm L/55 The appearance of new Soviet tanks such as the T-80B during the late 1970s and early 1980s led to the development of new technologies and weapons to counter the threat posed to Western armour. The T-80B had increased firepower and new composite ceramic armour. The T-72 also went through a modernization program in an attempt to bring it up to the standards of the T-80B. In 1985 the new T-72B version entered production, with a new laminate armour protection system; its turret armour, designed mainly to defeat anti-tank missiles, surpassed the T-80B's in protection. The German government began developing the Leopard 3, although this was canceled after the fall of the Soviet Union. On 29 October 1991, the governments of Switzerland, the Netherlands and Germany agreed to cooperate in the development of a modernization program for the Leopard 2. Part of this program included the introduction of a longer 120 mm tank gun, a cheaper alternative to a new tank gun, increasing the maximum range of the gun by an estimated . Although the gun is longer, allowing for longer and a higher peak pressure from the propellant, the geometry remains the same, allowing the gun to fire the same ammunition as that fired from the shorter version. The longer barrel allows ammunition to attain higher velocities; for example, with new kinetic energy penetrators ammunition can reach velocities of around . The new barrel weighs . Rh-120 L/55 A1 120mm The Rh-120-55 A1 is similar to earlier Rh-120 L/55 model. Compared to the L/44 and L/55, the L/55 A1 Extreme Service Condition Pressure (ESCP) is raised from , the Permissible Maximum Pressure (PMP) from , and the Design Pressure from . It is also known as the L/55A1 and entered service in 2018. The Rh-130 Future Gun System has a chrome-lined smoothbore barrel (initially L/51, Comparing pressure levels in the 120 mm L/55 A1 gun and in the 130 mm prototype, Extreme Service Condition Pressure climbs from , Permissible Maximum Pressure from , and Design Pressure from . In July 2020, Rheinmetall unveiled a testbed tank for the gun in a new turret, mounted on a Challenger 2 hull. In June 2022, Rheinmetall unveiled the Panther KF51 concept tank based on a Leopard 2 chassis and a redesigned turret hosting the new gun. According to Rheinmetall the Rh-130 mm cannon enables a 50% longer kill range compared to their 120 mm cannon with a higher rate of fire due to a fully automated ammunition handling system. ==Ammunition==

APFSDS DU round A variety of rounds have been developed for Rheinmetall's tank gun. For example, a long line of armour-piercing discarding sabot (APDS) rounds was developed by Rheinmetall. Originally, the Leopard 2 was outfitted with the DM23 kinetic energy penetrator, based on the Israeli 105 mm M111 Hetz which itself was a licensed copy of the American M735 round. The DM23 was eventually replaced by the DM33, which was also adopted by Japan, Italy, Netherlands and Switzerland. The DM33 has a three-part aluminium sabot and a two-part tungsten penetrator, and is said to be able to penetrate of steel armour at a range of . The DM43 is a further development of this round, codeveloped between Germany and France. The introduction of the longer barrel came together with the introduction of a new kinetic energy penetrator, the DM53. With the projectile including sabot weighing 8.35 kilograms with a 38:1 length to diameter ratio and with a muzzle velocity of , the DM53 has an effective engagement range of up to . A further development, called the DM63, improved upon the round by introducing a new temperature-independent propellant, which allows the propellant to have a constant pattern of expansion between ambient temperatures inside the gun barrel from to . The new propellant powders, known as surface-coated double-base (SCDB) propellants, allow the DM63 to be used in many climates with consistent results. The new ammunition has been accepted into service with the Dutch and Swiss, as well as German, armies. In 1993, South Korea invented a self-sharpening process on the tungsten heavy alloy (WHA) by applying microstructure control and multi-stage cyclic heat-treatment. Most penetrators in the world receive a single heat treatment, while Korean penetrators are treated 20 times using the new technology, which increases impact toughness by 300%. The self-sharpening effect increases penetration by 8–16% compared to regular penetrators, and compensates 6–10% less penetration from material disadvantage against depleted uranium (DU), providing firepower similar to DU ammunition in a DU particle-free environment. South Korea holds related patents in Japan, United Kingdom, United States, and 3 other unspecified nations. The public appearance of the K276 armour-piercing fin-stabilized discarding sabot (APFSDS), the first 120 mm ammunition with self-sharpening penetrator, was during the release ceremony of K1A1 prototype in 1996. The United States developed its own kinetic energy penetrator (KEP) tank round in the form of an APFSDS round, using a DU alloy long-rod penetrator (LRP), designated the M829, followed by improved versions. An immediate improvement, known as the M829A1, was called the "Silver Bullet" after its good combat performance during the Gulf War against Iraqi T-55, T-62 and T-72 tanks. The M829 series centres around the depleted uranium penetrator, designed to penetrate enemy armour through kinetic energy and to shatter inside the turret, causing a lot of damage within the tank. In 1998, the United States military introduced the M829A2, which has an improved depleted uranium penetrator and composite sabot petals. In 2002, production began of the ($10,000 per round) M829A3, using a more efficient propellant (RPD-380 stick), a lighter injection-molded sabot, and a longer (800 mm) and heavier (10 kg / 22 lb) DU penetrator, which is said to be able to defeat the latest versions of Russian Kontakt-5 explosive reactive armour (ERA). This variant is unofficially referred to by Abrams tank crews as the "super sabot". In response to the M829A3, the Russian Army designed the Relikt, the most modern Russian ERA, which is claimed to be twice as effective as the Kontakt-5. A further improved M829A4 round with a segmented penetrator to defeat Relikt entered full-rate production in December 2015. Both Germany and the United States have developed several other rounds. These include the German DM12 multi-purpose anti-tank projectile (MPAT), based on the technology in a high-explosive anti-tank (HEAT) warhead. The United States also has an MPAT-type projectile, named M830, later developed into the M830A1, which allows the M1 Abrams to use the round against helicopters. The M1 Abrams can use the M1028 canister round, which is an anti-personnel-anti-helicopter munition, packed with over 1,000 10 mm tungsten balls. The United States Armed Forces accepted a new demolition round, called the M908 obstacle defeating round, based on the M830A1 MPAT, but with the proximity fuse replaced by a hardened nose cap. The cap allows the round to impact and embed itself in concrete, exploding inside the target and causing more damage. The Israeli Army introduced a new round known as the laser homing anti-tank (LAHAT) projectile. Using a semi-active laser homing guidance method, the LAHAT can be guided by the tank's crew or by teams on the ground, while the missile's trajectory can be selected to attack either from the top (to defeat enemy armour) or frontally (to engage enemy helicopters). The missile can be fired by both and tank guns. The LAHAT has been offered as an option for the Leopard 2, and has been marketed by both Israel Military Industries and Rheinmetall to Leopard 2 users. Israeli Merkava tanks make use of the APAM round, an anti-personnel munition designed to release fragmentation at controlled intervals to limit the extent of damage. Fragments are shaped to have enough kinetic energy to penetrate body armour. Poland has introduced a series of projectiles for Rheinmetall's tank gun, including an armour-piercing penetrator target practice round (APFSDS-T-TP), a high-explosive round, and a high-explosive target practice (HE-TP) projectile. The ammunition is manufactured by Zakłady Produkcji Specjalnej Sp. z o.o. In early 2013 Rheinmetall announced two new rounds suitable for the L44 and the L55 guns, the DM11 HE round, designed for lightly armoured targets, field fortifications and targets behind cover, a lower cost alternative to the DM11, the HE SQ Rh31. In April 2024, the British Ministry of Defence announced that a statement of intent had been signed with Germany for the development of an Enhanced Kinetic Energy (EKE) armour-piercing round for both Challenger 3 and Leopard 2 tanks by Rheinmetall BAE Systems Land. Ammunition table ==Operators==

Due to tank sales, Rheinmetall's L/44 tank gun has been manufactured for other nations. For example, the Leopard 2 armed with the 44 calibre long gun, has been sold to the Netherlands, Switzerland, Sweden, Spain, Austria, Denmark, Finland, and other countries. Egypt had manufactured 700–800 M1A1 Abrams by 2005, and in 2008 requested permission to build another 125 tanks; their M256 main guns (the US version of the L/44) were manufactured by the US Watervliet Arsenal. The M1A1 has also been exported to Australia, while the M1A2 Abrams has been exported to Saudi Arabia and Kuwait. The Leopard 2A6 and its longer L/55 main gun have been exported for use by the Canadian Army, and the Netherlands upgraded part of its original fleet of Leopard 2s with the more powerful armament. The British Army has tested Rheinmetall's longer gun, possibly looking to replace the current L30A1 120 mm L/55 rifled main gun on the Challenger 2. Two Challenger 2s were modified to undergo firing trials. Although the South Korean K2 Black Panther is equipped with a CN08 120 mm L/55 main gun and is often misunderstood as a licensed product of the German counterpart due to its similar appearance of the gun barrel, it is indigenously developed by Agency for Defense Development (ADD) and WIA (Now Hyundai WIA), a Korea-based powertrain company affiliated with Hyundai Kia Motors Group. ==See also==