What is the M40 Recoilless Rifle?

The M40 106mm recoilless rifle is a portable, lightweight crew-served weapon that was designed by the United States as an anti-tank weapon. Although it is commonly describes as being 106mm, it is actually 105mm. The use of the 106mm designation was to prevent confusion with the incompatible 105mm ammunition that was used by the M27. Fired primarily from a wheeled ground mount, the M40 may also be employed in an antipersonnel role with the use of the antipersonnel-racer flechette round. This breech-loaded and air-cooled single shot rifle fires fixed ammunition and was designed for direct firing only.

The shape of the M40 is simple: a long tube with a M8C .50-caliber spotting rifle above it. The spotting rifle fires a round with the same trajectory as the 105mm round that then gives off a puff of smoke upon target impact. There is an elevating wheel located on the left hand side of the weapon with a trigger wheel in the center. This trigger wheel is used for fine tune adjustments to the elevation and, at the same time, firing the spotting rifle when pulled and the gun when pushed. The M40 is mounted on a tripod with a castor wheel attached to the front leg; on top of the wheel there is a traverse wheel. The rifle may be locked in traverse when the locking wheel is placed down.

Mounting for the M40 may be placed on an M151 Jeep for traveling or mobile use. Other vehicles, such as Willy’s Jeep M28A1, HMMWVs, Land Cruisers, and M274 Mechanical Mules have also been used to transport this weapon system. A special vehicle used by the United States Marine Corps, called the Ontos, has been known to carry six M40s at a time with a special M40 A1C T195E5 mount.

Ammunition for the M40 is issued in one-piece fixed cartridges. With the cartridge case and projectile crimped together, correct alignment may be ensured. This permits for faster loading, as the projectile and cartridge are loaded as one unit. The rear of the cartridge case is perforated, which allows the propellant gas to escape through the vented breech and neutralizes recoil. The M40 can fire many types of ammunition, including HEAT, HEP-T canisters, and High Explosive Anti Personnel.

Contact the defense experts at UDC USA for additional information on the M40 106mm recoilless rifle, other defense weapons, military training and education, and defense procurement services.