Armament of M1 Abrams

Primary armament of M1 Abram

M68A1 rifled gun

The main armament of the original model M1 Abrams was the M68A1 105 mm rifled tank gun firing a variety of high explosive anti-tank (HEAT), high explosive, white phosphorus and an anti-personnel (multiple flechette) round. This gun is a license-built version of the British Royal Ordnance L7 gun. While being a reliable weapon and widely used by many NATO nations, a cannon with lethality beyond the 3 kilometer range was needed to combat newer armor technologies. To attain that lethality, projectile diameter needed to be increased. The M68A1's performance in terms of accuracy and armor-piercing penetration is on par with the M256A1 up to 3 kilometers out, but beyond that range the 105 mm projectile lacks the kinetic energy to defeat modern armor packages.

M256 smoothbore gun

The main armament of the M1A1 and M1A2 is the M256A1 120 mm smoothbore gun, designed by Rheinmetall AG of Germany, manufactured under license in the United States by Watervliet Arsenal, New York. 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 M256A1 fires a variety of rounds. The M829A2 was developed specifically to address the threats posed by a Soviet T-90 or T-80U tank equipped with Kontakt-5 Explosive Reactive Armor. It also fires 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. The Abrams uses a manual loader, due to the belief that having a crewman reload the gun is faster and more reliable.

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 tungsten balls which spread from the muzzle to produce a shotgun effect lethal out to 600 m. The tungsten 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 covering fire. The canister round is also a highly effective breaching 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 XM1111 (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).

Secondary armament

The Abrams tank has three machine guns:

1. A .50 cal. (12.7 mm) M2 machine gun in front of the commander's hatch. On the M1, M1IP and M1A1, this gun is on a powered mount and can be fired using a 3× magnification sight, known as the Commander's Weapon Station (CWS for short), while the vehicle is "buttoned up" with all its hatches closed to protect the crew. On the M1A2 & M1A2SEP, this gun is on a flex mount (seen at right), the Commander having to expose himself to fire the weapon manually. With the forthcoming TUSK addon kit, an M2 or an Mk 19 grenade launcher can be mounted on the CROWS remote weapons platform (similar to the Protector M151 remote weapon station used on the Stryker family of vehicles). The upgrade variant called M1A1 Abrams Integrated Management (AIM) equips the .50 caliber gun with a thermal sight for accurate night and other low-visibility shooting.
2. A 7.62 mm M240 machine gun in front of the loader's hatch on a skate mount. Some of these have been fitted with gun shields during the ongoing conflict in Iraq as seen in the image at right, as well as night-vision scopes for low-visibility engagements.
3. A second 7.62 mm M240 machine gun in a coaxial mount to the right of the main gun. The coaxial MG is aimed and fired with the same computer fire control system used for the main gun.
4. (Optional) A second 12.7 mm M2 machine gun can be mounted directly above the main gun in a remote weapons platform as part of the TUSK upgrade kit mentioned below.

The turret is fitted with two six-barreled smoke grenade launchers (USMC M1A1s use an eight-barreled version). These can create a thick smoke that blocks both vision and thermal imaging, and can also be armed with chaff. The engine is also equipped with a smoke generator that is triggered by the driver. When activated, fuel is sprayed on the engine manifold, creating the thick smoke. However, due to change from diesel as a primary fuel to the use of JP-8, this system is disabled on most Abrams today, because JP-8 causes the tanks to catch fire when sprayed on the manifold. For the US Army in previous years, the Abrams usually maintained the provision for storing an M16 rifle or M4 carbine inside the turret in case the crew is required to leave the tank under potentially hostile conditions; while the crewmen were supplied with the M9 Beretta pistol as a personal sidearm. Considering the current (often dismounted) role of American armored crewmen and contemporary operating environments, though, current US Army crews maintain a rifle or carbine for each crewman. During Iraqi Freedom some crews were also issued M136 AT4 shoulder-fired anti-tank weapons under the assumption that they might have to engage heavy armor in tight urban areas where the main gun could not be brought to bear.