M40 recoilless rifle

M40 Recoilless Rifle
Greek infantry with an M40
Type	Recoilless rifle
Place of origin	United States
Service history
In service	Mid 1950s–present
Used by	See Users
Wars	Vietnam War Cambodian Civil War Algerian War Portuguese Colonial War Indo-Pakistani War of 1971 Rhodesian Bush War Western Sahara War Iran–Iraq war Lebanese Civil War Libyan Civil War Syrian Civil War
Production history
Manufacturer	Watervliet Arsenal
Specifications
Weight	209.5 kg (462 lb)
Length	3.404 m (11 ft 2 in)
Height	1.12 m (3 ft 8 in)
Shell	106×607mmR (HEAT, HEP, HEAP, Canister)
Caliber	105 mm (4.1 in)
Recoil	Recoilless
Carriage	Tripod
Elevation	−17° to +65° (between mount legs) −17° to +27° (over mount leg)
Traverse	360°
Muzzle velocity	503 m/s (1,650 ft/s) (M344 HEAT)
Effective firing range	1,350 m (1,480 yd)
Maximum firing range	6,870 m (M346A1 HEP-T)

The M40 recoilless rifle is a lightweight, portable, crew-served 105 mm weapon intended primarily as an anti-tank weapon made in the United States. The weapon is commonly described as being 106 mm, but it is in fact 105 mm; the 106 mm designation was intended to prevent confusion with the incompatible 105 mm ammunition from the failed M27. It could also be employed in an antipersonnel role with the use of the antipersonnel-tracer flechette round. It can be fired primarily from a wheeled ground mount. The air-cooled, breech-loaded, single-shot rifle fired fixed ammunition. It was designed for direct firing only, and sighting equipment for this purpose was furnished with each weapon.

The M27 recoilless rifle was a 105-mm weapon developed in the early 1950s and fielded in the Korean War. Although a recoilless rifle of this caliber had been a concept since the Second World War, the weapon was hurriedly produced with the onset of the Korean War. The speed with which it was developed and fielded resulted in problems with reliability caused by trunnions that were mounted too far to the rear. The M27 was also considered too heavy by the U.S. Army and had a disappointing effective range due to the lack of a spotting rifle. Taking the M27 as the basis for a new design, the Army developed an improved version of the M27 that was type-designated the M40 106-mm recoilless rifle in 1955. Originally, along with its type-designation, it was also given the official name BAT for Battalion Anti-Tank gun, but that was soon dropped. Although unsuitable for military purposes, M27 recoilless rifles were used to trigger controlled avalanches at ski resorts and mountain passes in the United States.

The M40 primarily saw action during the Vietnam War. It was later replaced by the BGM-71 TOW anti-tank missile system. The weapon was also used by anti-communist forces in Angola mounted on Land Rovers.