During M1 "Abrams" main battle tank serial production there were made some modernization stages. First stage begun in 1984 already, after four years after the beginning of the serial production, and projected to increase frontal defense and apply new M733 projectile with increased armor-piercing ability. This modification was idexed M1E1 and it was step to the new ability modification.

Second and third modernization stages were made accordingly in 1985 and 1988 and led developing M1 "Abrams" main battle tank modernization M1A1 as new modification had a number greater abilities than it’s predecessor. M1A1 differed firstly in greater firepower and increased defense. Since 1988 M1A1 modification was produced with built-in precipitant uranium armor. In 1986 first modernized M1A1 "Abrams" entered service in US Armed Forces. Firstly they were deployed in US tank forces in German Federation Republic.

M1A1 main battle tanks were built in Ohio state, Lima city, national tank plant and in Michigan state, Voren city, "Detroit Arsenal" tank plant. "General Dynamics" corporation was also producing M1A1 tanks under license. Production lasted till 1993 when it was changed to improved modification M1A2.

Main battle tank has classic arrangement with frontal drivers compartment. Hull and turret are welded with multi-layered frontal armor similar to British armor "Chobhem" bu additionaly increased with by precipitant uranium plates built-in in frontal hull and turret multi-layer armor. Similarly to British main battle tanks "Chieftain" and "Challenger", driver-mechanic with closed hatch is placed in half-lying position. It allowed greatly incline frontal armed plate in vertical inclination level such increasing defense from armor-piercing projectiles. Driver-mechanic use motorcycle-type steering wheel connected with automatic transmission.

Main battle tank firepower was increased by new M256 120-mm smoothbore main gun, produced in USA under German "Rheinmetall" company license. Similar gun was placed in German main battle tank "Leopard 2".

M256 combat load consists from unitary load with two main type projectiles: M827 undercaliber armor-piercing, with separating case and wolfram or percipient uranium heads; M830 multipurpose cumulative and high explosion-fragmentation projectiles. Furthermore there is a number of training projectiles. Every M1A1 projectile has flame able body and steel ground case. In case of greater dimension main gun’s rear part and projectiles, combat load was decreased to 40 from 55 used in M1 main battle tank. Armament load is placed in special built armed combat load compartment. Main gun is fitted with ejector and thermo sleeve body. Ammunition load compartment is separated from crew with armored screens. Ammunition load compartment has it's own hatch used to load ammunition storage. Furthermore it has special construction which blows off hatch and releases explosion energy threw it saving crew members, in case of direct hit into ammunition storage.

Additional armament consists from coaxial 7.62-mm machine gun, other the same caliber machine gun placed in front of loaders hatch and 12.7-mm anti-aircraft machine gun mounted on commanders observation turret. Tank's commander is able to use it with closed hatch. Main battle tank is fitted with thermo smoke equipment and L8A1 six-barrel smoke grenade launchers on each side of the turret boards.

There was also modernized fire control system. Tank was fitted with new commander’s panoramic thermovision sight, laser rangefinder and improved ballistic computer, which work in one complex with thermovision system. Digital ballistic computer counts-out quiet high accuracy fire correction angles. Data such as target’s range (from laser rangefinder), main gun’s axis inclination level, side wind speed, atmosphere temperature and pressure is automatically inserted while projectile type, it’s temperature, barrels channel wear level. There is scored target’s speed as well. All mentioned data allows to count-out projectile hitting target point.

M1A1 is fitted with "Honeywell" AGT-1500 gas turbine engine instead of similar "Avco Lycoming". Constructional changes radically increased weight and made developers to change engine to keep similar mobility characteristics, It has service life till major repair in 1 800 working hours or 15 000 km. Tank gas turbines greatly surpass diesel engines in service life which reaches only 600 - 900 working hours. However gas turbine engines have some disadvantages. Firstly they are tenfold more expensive and secondly they use from 20 to 50% more fuel. Engine is multi-fuel and use kerosene, diesel or petrol.

M1 "Abrams" has hydromechanic transmission made in one block with engine and has four forward and two backward gears. Tank turning radius is changing using consistent hydro changeable gear in turning mechanism. Chassis has 7 rubber laid bearing rolls, two track supporting bearings, leading and tracking wheels from each side. Main battle tank uses track with rubber-metallic hinge and full-rubber tracks. Monotorsion suspension with adjustable clearance allows changing bearing rolls dynamic clearance in 381 mm and full in 581 mm. Chassis and hulls boards are covered with anti-cumulation screens.

Main battle tank is equipped with Nuclear, Biological, and Chemical mass defeating weapons defense system, which provides cleaned air to crew’s face masks and increases compartment’s air pressure to prevent passing radioactive dust and poisons. M1A1 "Abrams" is also fitted with radiological and chemical reconnaissance equipment, fire prevention system, heater and communication sources.

There were built about 4 796 M1A1 "Abrams" main battle tanks for US Army and 221 for US Marines. In November 1998 there was made an agreement organizing in Egypt cooperation assemblage and serial production of 555 M1A1 main battle tanks for Egypt Armed Forces. The only Egypt main battle tank’s difference was usage of multi-layered armor similar to M1 version. Egypt rejected additional used in M1A1 "Abrams" precipitant uranium increased armor. Tanks were built in Egypt plant No.200 since year 1992. 40% of parts and equipments are made in this African republic while the other part is imported from USA. 77 M1A2 tanks have been built for US Army, 315 for Saudi Arabia and 218 for Kuwait and a number of tanks are used by Egypt.

Further M1A1 modification became M1A2 with new thermovision system, modernised laser rangefinder, battlefield informational system, modernized commander's observation turret, built-in dynamic armor.