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Development
The M1 Abrams was designed by Chrysler Defense (in 1979, General Dynamics Land Systems Division purchased Chrysler Defense Division) and is currently produced by General Dynamics Corporation in Lima, Ohio, and first entered US Army service in 1980. An improved version of the M1, the M1A1, was introduced in 1985.
The first M1A1 tanks to receive this upgrade were tanks stationed in Germany, since they were the first line of defense against the Soviet Union. US-based tank battalions participating in Operation Desert Storm received an emergency program to upgrade their tanks with depleted uranium armor immediately before the onset of the campaign.
M1A2 tanks uniformly incorporate depleted uranium armor, and all M1A1 tanks in active service have been upgraded to this standard as well, the armor thickness believed to be equivalent to 24 inches (610 mm) of RHA. The strength of the armor is estimated to be about the same as similar western, contemporary main battle tanks such as the Leopard 2. The M1A1/M1A2 can survive multiple hits from the most powerful tank munitions (including 120 mm depleted uranium APFSDS) and anti-tank missiles.[citation needed] In the Persian Gulf War, Abrams tanks survived multiple hits at relatively close ranges from Iraqi T-72s and ATGMs. M829A1 "Silver Bullet" APFSDS rounds from other M1A1 Abrams were unable to penetrate the front and side armor (even at close ranges) in friendly fire incidents as well as an incident in which another Abrams tried to destroy an Abrams that got stuck in mud and had to be abandoned.[3]
The main armament of the M1A1 and M1A2 is the M256A1 120 mm smoothbore gun, designed by Rheinmetall AG of Germany. The M256A1 is a variant of the Rheinmetall 120 mm L/44 gun carried on the German Leopard 2 on all variants up to the Leopard 2A5. Leopard 2A6 replaced the L/44 barrel with a longer L/55. The newer M256A1 is manufactured under license in the United States by Watervliet Arsenal, New York.
Rounds like the M829A2 were developed specifically to address the threats posed by a T-90 or T-80U tank, given their high level of protection provided the tanks by kontakt-5 Explosive Reactive Armor, and HEAT shaped charge rounds such as the M830, the latest version of which (M830A1) incorporates a sophisticated multi-mode electronic sensing fuse and more fragmentation which allows it to be used effectively against armored vehicles, personnel, and low-flying aircraft.
Unlike the Soviet-built tanks it was designed to go up against, the Abrams uses a manual loader rather than an automatic device, due to the belief that having a person reload the gun is faster and more reliable. This decision was proven out as the Soviet-era automatic loading system proved troublesome.[citation needed] Also important in the decision to use a crewmember instead of an automatic loader during the XM-1 development was the fact that autoloaders of the day did not allow for separate ammunition storage in the turret like the M1 was developed with.
A Marine M1A1 Abrams, 2nd Tank Battalion, fires its main gun into a building to provide suppressive counter fire against insurgents in Fallujah, Al Anbar Province, Iraq during Operation Al Fajr, 2004.The new M1028 120 mm anti-personnel canister cartridge was brought into service early for use in the aftermath of the 2003 invasion of Iraq. It contains 1,098 3/8 inch steel ball projectiles which spread from the muzzle to produce a shotgun effect lethal out to 600 m. The steel balls can be used to clear enemy dismounts, break up hasty ambush sites in urban areas, clear defiles, stop infantry attacks and counter-attacks and support friendly infantry assaults by providing cover-by-fire. The Canister round is also a highly effective breeching round and can level cinder block walls and knock man-sized holes in reinforced concrete walls for infantry raids at distances up to 75 meters.
In addition to this, the new MRM-KE (Mid-Range-Munition Kinetic Energy) is also in development. Essentially a cannon-fired guided round, it has a range of roughly 12 km and uses a KE warhead which is rocket assisted in its final phase of flight. This is intended to be the best penetrator yet, an improvement over the US 3rd generation DU penetrator (estimated penetration 790 mm).
http://en.wikipedia.org/wiki/M1_Abrams
