The M79 grenade launcher is a single-shot, shoulder-fired, break-action grenade launcher that fires a 40×46mm grenade, which uses what the US Army calls the High-Low Propulsion System to keep recoil forces low, and first appeared during the Vietnam War. Its distinctive report has earned it colorful nicknames, such as "Thumper", "Thump-Gun", "Bloop Tube", "Big Ed", "Elephant Gun", and "Blooper" among American soldiers[5] as well as "Can Cannon" in reference to the grenade size; Australian units referred to it as the "Wombat Gun".[6] The M79 can fire a wide variety of 40 mm rounds, including explosive, anti-personnel, smoke, buckshot, flechette (pointed steel projectiles with a vaned tail for stable flight), and illumination. While largely replaced by the M203,[7] the M79 has remained in service in many units worldwide in niche roles.