M60 Patton Tank

The M60 is an American second-generation main battle tank (MBT). It was officially standardized as the Tank, Combat, Full Tracked: 105-mm Gun, M60 in March 1959. Although developed from the M48 Patton, the M60 tank series was never officially christened as a Patton tank. The US Army considered it a "product-improved descendant" of the Patton tank's design. The design similarities are evident comparing the original version of the M60 and the M48A2. It has been sometimes informally grouped as a member of the Patton tank family. The United States fully committed to the MBT doctrine in 1963, when the Marine Corps retired the last ( M103) heavy tank battalion. The M60 tank series became America's primary main battle tank during the Cold War, reaching a production total of 15,000 M60s. Hull production ended in 1983, but 5,400 older models were converted to the M60A3 variant ending in 1990.

The M60 reached operational capability upon fielding to US Army European units beginning in December 1960. The first combat use of the M60 was by Israel during the 1973 Yom Kippur War, where it saw service under the "Magach 6" designation, performing well in combat against comparable tanks such as the T-62. In 1982 the Israelis again used the M60 during the 1982 Lebanon War, equipped with upgrades such as explosive reactive armor to defend against guided missiles that proved very effective at destroying tanks. The M60 also saw use in 1983 during Operation Urgent Fury, supporting US Marines in an amphibious assault on Grenada. M60s delivered to Iran also served in the Iran–Iraq War.

The United States' largest deployment of M60s was in the 1991 Gulf War, where the US Marines equipped with M60A1s effectively defeated Iraqi armored forces, including T-72 tanks. The United States retired the M60 from front-line combat after Operation Desert Storm, with the last tanks being retired from National Guard service in 1997. M60-series vehicles continue in front-line service with a number of countries' militaries, though most of these have been highly modified and had their firepower, mobility and protection upgraded to increase their combat effectiveness on the modern battlefield.

The M60 underwent many updates over its service life. The interior layout, based on the design of the M48, provided ample room for updates and improvements, extending the vehicle's service life for over four decades. It was widely used by the US and its Cold War allies, especially those in NATO, and remains in service throughout the world, despite having been superseded by the M1 Abrams in the US military. The tank's hull was the basis for a wide variety of prototype, utility and support vehicles such as armored recovery vehicles, bridge layers and combat engineering vehicles. As of 2015, Egypt is the largest operator with 1,716 upgraded M60A3s, Turkey is second with 866 upgraded units in service, and Saudi Arabia is third with over 650 units.

Development

Impetus

The United States entered a period of frenzied activity during the crisis atmosphere of the Korean War, when America seemed to lag behind the Soviet Union in terms of tank quality and quantity. Testing and development cycles occurred simultaneously with production to ensure speedy delivery of new tanks. Such rapid production caused problems but the importance given to rapidly equipping combat units with new tanks precluded detailed testing and evaluation prior to quantity production.

The M47 Patton entered production in 1951 and was used by the United States Army and Marine Corps but ongoing technical and production problems kept it from serving in the Korean War. The M48 Patton tank entered US service in 1952 but its early designs were deemed unsatisfactory by Army Field Forces (AFF). The improvements to the M48 focused on improving the 90mm main gun and fire control systems while simultaneously exploring the development of silicas glass composite armor and autoloader systems. The tank continued further development through 1955 in conjunction with its simultaneous mass production. The course of its development during the mid-1950s was the source of widespread debate among Congressional Budget Oversight committees.

The T95 program, which began in 1955 was intended to supersede the M48. It featured a host of innovative and experimental components such as its 90 mm smoothbore T208 cannon rigidly affixed to its turret, experimental X-shaped engine design using a vapour-cycle power plant fueled by hydrocarbons, composite armor and infrared rangefinder. The burden of developing them, however, slowed the overall program to a crawl. During the Hungarian Revolution of 1956, a Soviet T-54A medium tank was driven onto the grounds of the UK's embassy in Budapest by the Hungarians in November.

After a brief examination of this tank's armor by a British military attaché it was concluded that the 20-pounder (84mm L/66.7) was apparently incapable of consistently defeating its frontal armor with High-Explosive Anti-Tank (HEAT) or Armor-Piercing Capped (APC) ammunition. Its 100 mm gun was a significant advancement over the weapon of the T-44.

There were also rumors of an even larger 115 mm gun in the works. These events spurred the United Kingdom to begin upgrading existing tanks with a 105mm high-velocity rifled gun in 1958, the Royal Ordnance L7 to keep the Centurion viable against this new Soviet tank design. The United States responded by starting development of the XM60 tank in September 1957. This new tank design incorporated many Army Combat Vehicle (ARCOVE) committee improvements to the M48A2, chiefly the use of diesel engines to increase its operational range and the use of a more powerful main gun.

Choice of components

M68 105 mm main gun

The main gun was chosen after a comparative firing test of six different guns carried out on the Aberdeen Proving Ground in 1958. The factors evaluated were accuracy, lethality of a hit, rate of fire and penetration performance.

An M48A2C was fit with the 90 mm M41 and tested with the new T300E53 HEAT round. A smoothbore version of the 90 mm, the T208E9, was mounted on the T95E1 tank and tested the T320E62 Armour-Piercing Discarding Sabot (APDS) round. An American variant of the British Royal Ordnance L7 tank gun, under the US designation 105 mm T254E1, was mounted on the T95E2 and tested with British APDS ammunition. Finally, two versions of the 120 mm gun from the M103 were trialed, the existing M58 model and a lightened variant known as T123E6 which was mounted on the T95E4.

The T123E6 was preferred by the Ordnance Department because its ammunition, the same as that for the M58 gun, was already at an advanced state of development. However the ammunition was in two parts, shell and propellant bag, which required significant time to load. In the M103 this was addressed by adding a second loader, but a medium tank would not have the internal space needed for another crewmember and the firing rate would suffer as a result. In testing it demonstrated a maximum rate of 4 rounds per minute vs. the T254's 7 rpm.

Based on these tests, the 105 mm T254E1 was selected, modified to the T254E2 and standardized as the "Cannon, 105mm Gun, M68". It used a vertical drop breechblock instead of the T254E1's horizontal sliding breechblock. Until Americ