M2 Mortar

The M2 mortar is a 60 millimeter smoothbore, muzzle-loading, high-angle-of-fire weapon used by U.S. forces in World War II, the Korean War, and the Vietnam War for light infantry support.

History and description

During the late 1920s, the US Army began examining mortars to act as light infantry support weapons for company level fire support, bridging the gap between medium mortars and hand grenades. In the late 1930s, the War Department eventually settled on a 60 mm design from Edgar Brandt, a French ordnance engineer.Norris, John and Calow, Robert, ''Infantry Mortars of World War II'', Osprey Publishing (2002), , , p. 15 The Ordnance Department purchased eight of the French-built weapons in 1938, standardizing them as the Mortar, 60 mm, M1. When production drawings were revised by Watervliet Arsenal to adopt standard American threads, tubes, and plates, the weapon was redesignated the Mortar, 60 mm, M2. In January 1940, the first production contract for 1,500 mortars was issued to the Read Machinery Company of York, Pennsylvania. As requirements rose in 1940, another contract was placed with the Danville, Pennsylvania-based Kennedy-Van Saun Engineering Company. Requirements declined early in 1944, but by the end of the year, demand increased and exceeded existing supply. The War Department ordered Kennedy-Van Saun to increase production, and also added a contract from the Firestone Tire and Rubber Company; production of the M2 during the first eight months of 1945 totaled 30,152, nearly equaling that of the previous three years.

Although classed as a light mortar, the M2 had considerable range compared to similar 50 mm and 60 mm-caliber weapons like the British Ordnance SBML two-inch mortar, Soviet RM-38 and related models, and German 5 cm Granatwerfer 36, with its fixed-firing pin design allowing for a high rate of fire by trained crews. Normally employed by weapons platoons of U.S. infantry companies, the M2 is of the usual mortar pattern of the day. It consists of a smoothbore metal tube on a rectangular baseplate, supported by the simple M5 bipod to which are attached elevation and traverse mechanisms. The firing pin was fixed in the base cap of the tube, firing the bomb automatically when it was dropped down the barrel. The weapon was used throughout World War II by the U.S. Army and U.S. Marine Corps. It saw service again in the Korean War, and by French forces in their counterinsurgency campaigns in Indochina and Algeria.

The VPA used many M2 mortars captured from France (equipped by the US) and self-produced, equipped to companies and battalions.

It was used under designation ''m/952'' by Portugal during the Portuguese Colonial War. During the Vietnam War, the M2 was again used by the U.S. Army and marines, as well as by South Vietnamese forces. Ultimately, the M2 was replaced by the M224 in 1978.

Chinese variants

China (the Republic of China prior to 1949) also locally produced the M2 mortar, which was designated as the ''Type 31''. After the People's Republic of China was established in 1949, some Type 31s were supplied to North Korea and North Vietnam. It was later modified as the ''Type 63'' and were supplied to Mujahideen rebels during Soviet-Afghan War. A variant called ''Type 63-1'' has been produced under license by the Pakistan Machine Tool Factory Limited and by the Helwan Machine Tools Company in Egypt.

Operation

Each mortar shell had a screw-on cap in its base. Inside the hollow in the tail, it contained a 20-gauge M5A1 ignition cartridge. This was a paper shotgun shell filled with ballistite powder.

The mortar had a firing pin in the bottom of the tube. When the shell was dropped down the tube, the firing pin struck the ignition cartridge in the shell's tail, detonating it. When the cartridge detonated, the explosive gases exited the base of the shell through two bleed holes. This propelled the shell out of the tube in an arc. Unassisted, the mortar shell had a range of about .

To increase the mortar's range, shells were issued with four waterproof cellophane bags of propellant, called increments, fastened to the stabilizing fins with wire clips. The ignition cartridge would ignite the propellant, increasing chamber pressure and the shell's muzzle velocity. All four increments and the ignition cartridge pushed the maximum range to about at 45 degrees elevation (depending on the shell's length and weight). To reduce the mortar's muzzle velocity, increment charges were removed as needed before firing. This allowed great flexibility in the angle at which shells impacted the target area, allowing the weapon to drop shells behind hills or buildings.

Ammunition

The M2 Mortar could fire several types of ammunition.
* ''M49A2 high explosive (HE) with point detonating fuze M52B1'' otal weight: , filler weight: of TNT An explosive shell used against infantry and other light area targets. It has a minimum range of when fired without a boosting charge at a 70° angle and a maximum range of when fired with four boosting charges at a 45° angle.
* ''M49A3 high explosive cartridge (HE) with super-quick point detonating fuze M525'' eight: 3.05 lb (1.38 kg) Often referred to in the field as "HE quick".
* ''M302 white phosphorus cartridge (WP):'' A "bursting smoke" shell used as a signaling, screening, smoke-producing, and casualty-producing shell.
Unlike regular smoke shells of the period, which used a "hot" chemical reaction to generate a smoke cloud, the white phosphorus shell detonates to expose its filler to the air, causing it to spontaneously ignite and generate a thick cloud of white or grey smoke. It also sets combustible materials in its radius of effect on fire, causing secondary smoke sources. If personnel are hit by burning white phosphorus, the fragments will continue to burn inside the wound. They need to be evacuated to a hospital to have the fragments removed under special conditions.
* ''M83 illuminating cartridge (ILL):'' A pyrotechnic parachute flare shell used in night missions requiring illumination for assistance in observation.
* ''M69 training/practice cartridge (TP)'' eight: 4.43 lb (2.01 kg) A shell with a cast iron body, inert filler, and detachable fin assembly used to train recruits in firing the M2 mortar. The cast iron body is reusable and the fin assembly can be replaced if damaged.
* ''M50A3 training/practice cartridge (TP)'' eight 3.15 lb (1.43 kg) This practice shell is ballistically matched to the M49A4 HE shell, making it easier for training. They are the same size and weight, only differing in that the M50A3 is inert and emits a puff of white smoke on impact.

Users

*
*
*
* : Type 63
*
* : Type 31, Type 63 and Type 63-1
* : designated ''m/51''
*: Type 63-1 produced under license.
* : used by the Kagnew Battalion
*
*
*
*
*
* : Type 63
*
* : Type 31
*: The Armed Forces was equipped with 579 M2/M19s before the Korean War, and 2,263 were in service with the Army by the end of the war. Began replacing with KM19 in the 1970s.
*
*
*
* : Type 63-1 produced under license.
*
*
*
*
*
* Type 31
*
*: M2, Type 31 and Type 63

See also

* List of U.S. Army weapons by supply catalog designation
* M1 mortar
* M2 4.2-inch mortar - A 107 mm infantry mortar
* M224 mortar - Replacement for the M2 in US service
* CM60A1
* List of weapons of the Lebanese Civil War
* List of weapons of the Portuguese Colonial War
* List of weapons of the Rhodesian Bush War
* List of weapons of the Vietnam War

References

* Hogg, Ian (2000). ''Twentieth-Century Artillery''. Friedman/Fairfax Publishers.
* Norris, John and Calow, Robert, ''Infantry Mortars of World War II'', Osprey Publishing (2002),

External links

Cover photo of M2 60mm mortar
May 1941 Popular Science

{{U.S. chemical weapons

World War II mortars
Chemical weapon delivery systems
Infantry mortars
Mortars of the United States
World War II infantry weapons of the United States
World War II infantry weapons of China
Chemical weapons of the United States
60mm mortars
Weapons and ammunition introduced in 1940