The M20 is a recoilless rifle of US origin. It was developed during the later stages of World War 2 to provide infantry with a longer range anti-tank weapon than the Bazooka. The M20 recoilless rifle should not be confused with the M20 Super Bazooka which is a contemporary rocket launcher also of US origin.

The M20 is a breech loaded recoilless rifle with a rifled barrel to spin stabilized the projectiles during flight. It uses a conventional breech loading mechanism and fires a variety of 75mm rounds. An optical sight is fitted that can be used for both direct and indirect fire. The M20 uses the M1917 tripod and requires at least two men to operate.

The M20 fires 75mm rounds through a rifled barrel. The ammunition types include HEAT, HE, HEP and WP. When fired in a ballistic trajectory the round may reach well over 3km, but the effective range is about 400 meters for HEAT rounds and 1 km for HE rounds. The armor piercing ability is 100 mm RHA which made it difficult but not impossible to take out a Soviet T-34 tank. Against infantry and bunkers the M20 proved very effective, even at extended ranges.

Most M20 were mounted on the M1917 tripod and can be carried over short distances. The M20 with M1917 tripod could also be easily carried by a jeep and be fired from the vehicle, allowing it to reposition quickly. The M20 was also used on a pintle mount on the M29 Weasel.

The primary user of the M20 was the United States that extensively used the M20 during the Korean War. By the 1970's the M20 was completely replaced by guided anti-tank missiles and during the transition period many M20's were exported. China also produced and used a copy of the M20 and exported it to many communist allies. Nowadays the M20 is considered obsolete, but limited quantities remain in use in third world nations.