The first M1 Abrams tank originally featured a 105 mm M68A1 gun due to cost concerns in getting the Abrams into service. However, after its acceptance in 1981, the US military began considering the more powerful 120 mm Rheinmetall smoothbore gun for use on the Abrams. Following a trial period with the M1E1 prototype equipped with the 120 mm M256 gun, the vehicle was officially accepted into service in 1984 as the M1A1 Abrams, with production lasting from 1985 to 1993. The M1A1 would set the standard for the modern Abrams design, becoming the most numerous base version produced, with around 5,000 units manufactured (including retrofits of older M1 and IPM1 tanks to M1A1 standards). It would most notably see combat in US campaigns in the Middle East, such as the 1991 Operation Desert Storm and the 2003 Operation Iraqi Freedom. The M1A1's ubiquity paved the way for various M1A1 upgrades, foreign sales, and the improved M1A2 Abrams.

Introduced in Update 1.87 "Locked On", the M1A1 gives the highly mobile Abrams platform the deadly 120 mm M256 gun to use against enemy tanks. The round selection is limited to APFSDS and HEAT-FS; the APFSDS rounds allow for a more even fight against opposing tanks, though the M1A1 may still need to aim for weak points against better-protected opponents. The composite armour of the M1A1 retains effective chemical protection and, against downtier opponents, offers good resistance to kinetic shells. However, against stronger opponents, players must rely on the M1A1’s mobility to avoid being hit. Its excellent "soft" protection, such as the blow-out panels for the turret bustle ammo racks, can help prevent an ammunition cook-off from outright destroying the tank.