Starting in 1988, tanks M1A1 received the packages improved of armor which incorporated the mesh out of uranium exhausted in their armor in front of the turret and the hull. The armor reinforced this manner resistance appreciably increased of offers towards all the types of the armaments anti-tank device, but at the expense adding the considerable weight to the tank. First tanks M1A1 to receive this leveling were tanks posted in Germany, since they were the first line of defense against the Soviet Union. In addition to the Abrams' advanced armor, some Abrams, most notably M1A1s of the US Marine Corps, are equipped with a Missile Countermeasure Device that can detect and jam the guidance systems of laser-guided anti-tank guided missiles (ATGM).



This device is mounted on the turret roof in front of the Loader's hatch, and can lead some people to mistake Abrams fitted with these devices for the M1A2 version, since the Commander's Independent Thermal Viewer on the latter is mounted in the same place, though the MCD is box-shaped and fixed in place as opposed to cylindrical and rotating like the CITV. The main armament of the original model M1 was the M68A1 105 mm rifled tank gun firing a variety of HEAT, high explosive, white phosphorus (smoke), and a highly efficient and lethal anti-personnel (multiple flechette) round. This gun is a license-built version of the British Royal Ordnance L7 gun.

While being a reliable weapon, the 105 mm was becoming obsolete in the face of advances in armor technology, which meant that a better tank gun was needed for the M1. The main armament of the M1A1 and M1A2 is the M256 120 mm smoothbore gun, designed by Rheinmetall AG of Germany. The M256 is a variant of the Rheinmetall 120 mm L/44 gun manufactured under license in the United States by General Dynamics Land Systems Division in their plant in Lima, Ohio. It is the same armament carried by the German Leopard 2 tank up to the version A5 until replaced by the longer L/55 gun in version A6.