M252 mortar

The M252 81 mm medium weight mortar is a British-designed smooth bore, muzzle-loading, high-angle-of-fire weapon used for long-range indirect fire support to light infantry, air assault, and airborne units across the entire front of a battalion zone of influence. In the U.S. Army and U.S. Marine Corps, it is normally deployed in the mortar platoon of an infantry battalion.

The M252 system weighs 91 lb (41 kg) completely assembled and is composed of the M253 Cannon (35 lb (16 kg)), M177 Mount (27 lb (12 kg)), M3A1 Baseplate (29 lb (13 kg)), and the M64A1 Sight Unit (2.5 lb (1.1 kg)). The mount consists of a base plate and a bipod, which is provided with screw type elevating and traversing mechanisms to elevate/traverse the mortar. The M64A1 sight unit (also used on the M224) is attached to the bipod mount. The M252 is a gravity-fired smoothbore system. Attached to the muzzle of the weapon is the Blast Attenuation Device (BAD), used to reduce the blast effects on the mortar crew. To increase cooling efficiency, the breech end is finned; though first-hand accounts attest that the level of cooling is negligible. ^{[citation needed]} The cannon also has a crew-removable breech plug and firing pin.

High explosive rounds fired by the M252 weigh 10 lb (4.5 kg) with 0.7 kg of explosive filler and can have an effective kill radius of 115 ft (35 m).

In 2017, the Marines revealed they were developing precision-guided rounds for the 81 mm mortar, similar to efforts for the 120 mm Expeditionary Fire Support System but in a man-portable system.

The M252 is an adaptation of the British 81mm L16A2 mortar developed in the 1950s. It entered service with the U.S. Army and replaced the previous 81 mm M29 mortar in 1987. It was adopted due to the extended range (4,500 to 5,650 m (4,920 to 6,180 yd)) and enhanced lethality. In the U.S. it is produced by Watervliet Arsenal.

A lightweight version, the M252A1 was first fielded in December 2014. By using lightweight materials such as aluminum, titanium and nylon kevlar the total weight was reduced by 12 pounds (5.4 kg) to 79 pounds (36 kg). The M252A1 also required less maintenance with its grease-less internal gears. The M252A1 was scheduled to replace the M252 in 2016. In November 2016, the Watervliet Arsenal received a contract to produce the bipods which have an A-shaped bipod frame with deliveries to be completed by March 2020. As part of the same program, a lightweight version of the M224 60mm mortar the M224A1 was also developed. The Marines developed an improved M252A2 version that weighs about 8.16 kg (18.0 lb) less than the original and incorporates a 4× magnification sight with a new cooling system.

A crew of five enlisted personnel operate the M252: the squad leader, the gunner, the assistant gunner, the first ammunition bearer, and the second ammunition bearer.

While the M252 does fire a weapon-specific series of ammunition, it can also fire rounds from the M29 Mortar (only at charge 3 or below though). The M252 Mortar can fire the following principal classifications of training and service ammunition: