M20 recoilless rifle

For the M20 super-bazooka, see Bazooka.

The M20 recoilless rifle is a U.S. 75 mm caliber recoilless rifle T21E12 that was used during the last months of the Second World War and extensively during the Korean War. It could be fired from an M1917A1 .30 caliber machine gun tripod, or from a vehicle mount, typically a Jeep. Its shaped charge warhead, also known as HEAT, was capable of penetrating 100 mm of armor. Although the weapon proved ineffective against the T-34 tank during the Korean War and most other tanks, it was used primarily as a close infantry support weapon to engage all types of targets including infantry and lightly armored vehicles. The M20 proved useful against pillboxes and other types of field fortifications.

M20 recoilless rifle
An M20 recoilless rifle in action during the Korean War
Type	Recoilless anti-tank weapon
Place of origin	United States
Service history
Used by	United States
Wars	World War II Korean War First Indochina War Algerian War^[1] Portuguese Colonial War Lebanese Civil War Vietnam War Salvadoran Civil War Western Sahara War
Production history
Designed	1944
Produced	1945
Variants	Type 56
Specifications
Mass	103 lb (47 kg)
Length	82 in (2.1 m)
Barrel length	65 in (1.7 m)
Crew	1 or 2^[2]
Shell	75 x 408 mm R^[3] HE, HEAT, Smoke
Shell weight	20.5–22.6 lb (9.3–10.3 kg)
Caliber	75 mm (3.0 in)
Recoil	Recoilless
Carriage	M1917A1 tripod
Elevation	−27° to +65°
Traverse	360°^[2]
Muzzle velocity	1,000 ft/s (300 m/s)
Maximum firing range	3.9 mi (6.3 km)^[2]

An M20 recoilless rifle on display in the Royal Armouries at Fort Nelson

Sergeant Reckless, a decorated war horse serving with a US Marine Corps recoilless rifle platoon in the Korean War, stands beside a 75mm recoilless rifle

History

During World War II, the U.S. military recognized that, due to advancements in armor technology by enemy forces, a powerful lightweight weapon was needed to defend infantry and light armor units. The Ordnance Department Small Arms Division commenced development of a recoilless rifle and, by 1944, models of a 75 mm recoilless rifle were being tested. Production of the M20 was underway by March 1945; only limited numbers were used by Allied troops in the European and Pacific theaters.

The M20 relied on a perforated artillery shell casing, combined with a rear vented breech using propellant gases from the firing of a shell, to greatly reduce the recoil of the weapon. It is this use of vented propellant gases that eliminated the need for a recoil system, thereby reducing the weight of the launcher and enhancing its use as a light infantry weapon.

The M20 was one of the main anti-tank weapons used by the U.S. military in the early days of the Korean War along with the 2.36-inch Bazooka. However, the recoilless rifle failed to destroy any North Korean T-34-85 during the Battle of Osan on July 5, 1950. After the deployment of the 3.5-inch M20 Super Bazooka in mid-July, the M20 recoilless rifle no longer functioned as an anti-tank weapon, and was used as an infantry support weapon. It was a very effective weapon to destroy enemy bunkers and trenches with easy transportation benefitted from light weight while providing great firepower.^[4]

Recoilless rifles, such as the M20, were also used successfully in large numbers by both sides in the First Indochina War (1946–54). They were phased out after being replaced by wire guided missiles, which were introduced during the Vietnam War in the 1960s and 1970s. Until stockpiles of ammunition were exhausted in the 1990s, M20 recoilless rifles were used to start controlled avalanches by the U.S. National Forest Service and National Park Service.^[5]

The Royal Moroccan Army used M20s during the Western Sahara War against the Polisario Front.^[6]

China also produced unlicensed copies, known as the Type 52 and Type 56 (an upgraded version that could fire fin-stabilized HEAT shells). These versions were widely used by the North Vietnamese Army (NVA) and Vietcong guerrillas in the Vietnam War^[7] and there are also pictures suggesting its use by guerrillas and militias in the Lebanese Civil War (1975–1990), such as the Amal Movement militia.^[8]

Operators

•   Albania: Type 56^[9]
•   Argentina: M20^[10]
•   Brazil: M20^[10]
•   Burkina Faso: Type 52^[10]
•   Burundi: Type 52^[10]
•   Cameroon: Type 52^[11]
•   Colombia: M20^[10]
•   Democratic Republic of the Congo: M20^[10]
•   People's Republic of China: Type 52 and Type 56^[10]
•   El Salvador^[10]
•   Ethiopian Empire: M20s were used by the Kagnew Battalion^[12]
•   France
•   Guinea-Bissau: Type 52^[10]
•   Indonesia: Type 52 and Type 56 used by Indonesian Marine Corps^[13]
•   Lebanon
•   Mauritania: M20^[10]
•   Myanmar:Both US M-20 and Chinese Type 52 and Type 56^{[citation needed]}
•   Netherlands^[14]
•   Niger: M20^[10]
•   Pakistan: Type 52^[10]
•   Paraguay: M20^[10]
•   Philippines: M20^[10]
•   Saudi Arabia: M20^[10]
•   South Korea: The Armed Forces began receiving M20s from the U.S. in 1951, and 601 were in service with the Army by the end of the Korean War.^[4]
•   Tanzania: Type 52^[10]
•   Togo: Type 56^[10]
•   United States
•   Vietnam: Type 52 and Type 56^[10]
•   South Vietnam: M20^[15]
•   Turkey: M20^[16] 617 units.
•   Yemen: M20^[10]
•   Yugoslavia: M20^[10]
•   Zambia: M20^[10]

See also

• M18 recoilless rifle – smaller 57mm model of the same era
• M40 recoilless rifle
• M29 Weasel – the "M29C Type A" variant had a center-mounted M20 as its armament
• List of weapons of the Lebanese Civil War
• Weapons of the Vietnam War
• Weapons of the Cambodian Civil War
• Weapons of the Laotian Civil War

Notes

1. Huon, Jean (March 1992). "L'armement français en A.F.N." Gazette des Armes (in French). No. 220. pp. 12–16.
2. Chamberlain, Peter (1975). Infantry, mountain, and airborne guns. Gander, Terry. New York: Arco. p. 58. ISBN 0668038195. OCLC 2067391.
3. "75-77 MM CALIBRE CARTRIDGES". www.quarryhs.co.uk. Retrieved 2017-10-02.
4. Bak, Dongchan (March 2021). Korean War : Weapons of the United Nations (PDF) (in Korean). Republic of Korea: Ministry of Defense Institute for Military History. pp. 71–75. ISBN 979-11-5598-079-8.
5. "United States Military Artillery for Avalanche Control Program:A Brief History in Time" (PDF). USDA Forest Service National Avalanche Center. Retrieved 2018-04-11.
6. Anthony Cordesman (2016). After The Storm: The Changing Military Balance in the Middle East. Bloomsbury Publishing. p. 112. ISBN 978-1-4742-9257-3.
7. Rottman, Gordon L. (10 Feb 2009). North Vietnamese Army Soldier 1958–75. Warrior 135. Osprey Publishing. p. 32. ISBN 9781846033711.
8. A Toyota Land Cruiser BJ40/42 of the AMAL militia in 1984 armed with a Chinese made Type 56 75mm recoilless rifle.
9. partisan1943 (April 2018). "Eastern Bloc militaries". Eastern Bloc militaries. Retrieved 2021-10-05.
10. Gander, Terry J.; Cutshaw, Charles Q., eds. (2001). Jane's Infantry Weapons 2001/2002 (27th ed.). Coulsdon: Jane's Information Group. ISBN 9780710623171.
11. International Institute for Strategic Studies (2021). The Military Balance. p. 455. ISBN 9781032012278.
12. "Ethiopians in the Korean War: WWII gear used". wwiiafterwwii.wordpress.com. August 18, 2016.^{[self-published source]}
13. Jalesveva Jayamahe, p.125
14. Park, Il-Song; Yang, Yong-Jo; Son, Kyu-Suk. "The Korean War and the Forces of the Kingdom of Netherlands". A History of Netherland Forces' Participation in the Korean War (PDF). Translated by Lee, Jang-Song. Ministry of Patriots and Veterans Affairs (South Korea). pp. 67–68.
15. Gordon L. Rottman (2010). Army of the Republic of Vietnam 1955–75. Vol. Men-at-Arms 458. Osprey Publishing. p. 7. ISBN 9781849081818.
16. . 2018-08-08. Archived from the original on 2018-08-08. Retrieved 2021-05-03.

References

• TM 9-2300 Artillery Materiel and Associated Equipment. dated May 1949
• TM 9-314 operators, and maintenance
• SNL C-74 parts

External links

 

Wikimedia Commons has media related to M20 recoilless rifles.

• The short film STAFF FILM REPORT 66-21A (1966) is available for free viewing and download at the Internet Archive.