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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 Western powers
Wars Vietnam War
Production history
Manufacturer Watervliet Arsenal
Weight 209.5 kg
Length 3.404 m
Height 1.12 m

Shell 106 × 607 mm. R (HEAT, HEP, HEAP, Canister)
Caliber 105 mm.
Recoil Recoilless
Carriage Tripod
Elevation -17 to +65º
Traverse 360º
Rate of fire 1 rpm
Muzzle velocity 503 mps (M344 HEAT)
Effective range 1350 m
Maximum range 6870 m (M346A1 HEP-T)[1]

The M40 recoilless rifle was 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 designed 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 conflict in Korea. 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 a 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.[2] Although unsuitable for military purposes, M27 recoilless rifles were used to trigger controlled avalanches at ski resorts and mountain passes in the United States.[3]

The M40 primarily saw action during the Vietnam War and 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 Landrovers.



The M40 is shaped like a long tube with a 0.50 cal spotting rifle above. On the left hand side, there is an elevating wheel, in the centre of which is the trigger wheel used to fine adjust the elevation and at the same time firing the spotting rifle when pulled, and the gun when pushed. The mounting is a tripod, but the front leg has a castoring wheel. On top of the mount is a traverse wheel. On the centre of the traverse wheel is a locking wheel, when the wheel is down, the rifle is locked in traverse, and can only be moved right and left with the traverse wheel. When the wheel is raised, the rifle can be traversed by hand. Austria produced a two-wheeled mount for the M40.

The whole mounting can be placed on an M151 Jeep for mobile use. It has also been mounted on Land Rover Defenders, M113s, Mercedes-Benz G-Wagen, HMMWVs, Toyota Land Cruisers, AIL Storms and M274 Mechanical Mules. They were also used on US Navy Minesweepers (MSO) during operation Market Time in Viet Nam.

A special vehicle called Ontos carried six M40's. A version specific to the T195E5 mount, the M40A1C, was used. It was used only by the U.S. Marine Corps. Japan produced a self propelled gun called the Type 60 which carried two side by side. Some Pakistani M113s have a dual mounting.

The M40 was a very successful export item and continues to be used by South Korea (ROK), Egypt, Estonia, Greece, Honduras, Iran, Israel, Lebanon, Malaysia, Mexico, Morocco, the Philippines, Taiwan (Republic of China Marine Corps), Turkey, Colombia, Cambodia, Vietnam, and many others.


Ammunition for the 105 mm rifle was issued as one-piece fixed cartridges. The term "fixed" means that the projectile and the cartridge case are crimped together. This ensures correct alignment of the projectile and the cartridge case. It also permits faster loading because the projectile and the cartridge case are loaded as one unit. The rear end of the cartridge case is perforated, to allow the propellant gas to escape through the vented breech, thus neutralizing recoil. The projectiles used are pre-engraved, that is, the rotating bands are cut to engage the rifled bore.

Types of ammunition included HEAT, High Explosive Plastic-Tracer (HEP-T), canister, High Explosive Anti Personnel, and the M368 dummy round which could not be fired and was used for crew drill. The original U.S. HEAT round penetrated more than 400 mm of armor. Near the end of the M40's service life, both Austria and Sweden produced HEAT rounds for the weapon capable of penetrating more than 700 mm of armor.[4]

Producer Round
Type Proj
United States M581 APERS 9.89 kg flechettes 4.94 kg N/A 300 m
Spain M-DN11 HEAP 3.6 kg Hexogen 0.77 kg N/A 1500 m
France NR 483 HEAP 7.8 kg Comp. A3 N/A N/A N/A
Italy PFF HE 9.89 kg Comp. B N/A N/A N/A
United States M346A1 HEP-T 7.96 kg Comp. A3 3.5 kg N/A[5] N/A
United States M344A1 HEAT 7.96 kg Comp. B 1.27 kg over 400 mm[6] 1350 m
Sweden 106 3A HEAT-T 5.5 kg Octol 1.0 kg over 700 mm[7] 2000 m
Austria RAT 700 HEAT 5.0 kg N/A 1.1 kg over 700 mm N/A

The ammunition for the 0.50 cal spotting rifle is not .50 BMG. The round used is a special round designed to simulate the flight path of the 105 mm ammunition.


Photo Gallery



  1. ^ U.S. Army Technical Manual 43-0001-28, p. 5-27, April 1994.
  2. ^ John Weeks, Men against tanks, New York: Mason/Charter, 1975.
  3. ^ Comment by Ken Estes at
  4. ^ JAH, pp. 140-141.
  5. ^ Probably defeats ~ 200 mm of armor.
  6. ^ JIW.
  7. ^ After penetrating explosive reactive armor.
  8. ^­_Recoilless_Rifle_Syst.htm


  • (JAH) Terry Gander and Ian Hogg (ed.), Jane's Ammunition Handbook 1994, Coulsdon: Jane's Information Group Ltd., 1993.
  • (JIW) Richard Jones and Leland Ness (ed.), Jane's Infantry Weapons 2007-2008, Coulsdon: Jane's Information Group Ltd., 2007.

External links

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