Aerojet XM174

History of the Aerojet XM174

The XM174 was an experimental 40mm automatic grenade launcher that emerged from combat during the Vietnam War. The design was proposed by Aerojet Ordnance Manufacturing Company in 1968 and sought to combine form and function with the air-cooled Browning M1919A4. The 30 caliber machine gun has the firepower of a 40mm shell.

The repeat fire feature will allow the gunner to suppress enemy forces or drive out burrowing enemies with direct or indirect fire. The weapon was only tested during the Vietnam conflict, but was never officially adopted by the U.S. armed forces.

The XM174 retains most of the appearance of the original M1919A4 machine gun, including its rectangular receiver, obvious charging handle and rear grip. The main visual change is the integration of a large barrel assembly designed to deliver low velocity 40x46mm grenades. Of course, this forced a major overhaul of the M1919 system's interior, with ammunition fed from a 12-round detachable drum mounted on the left side of the receiver. The spent cartridges are ejected through the opening on the right.

Sightings were made through iron shutters in front of the receiver. The XM174 recorded a rate of fire of 350 rounds per minute, fired by motion induced by basic recoil. The total weight of the system is 7.25 kg.

The XM174 has been tried in many ways - as a portable, crew-operated unit and vehicle support weapon. In the former, the gun is strapped to a heavy-duty tripod assembly that helps with lateral and height. Pointing feet to keep the weapon firmly planted in the ground, two legs stretched back and one leg forward. This then requires the crew to sit behind the gun in the traditional way, or fire from a semi-recumbent position when they are under fire.

For the latter approach, weapon systems are mounted on trunnion mounts to allow for trainable firepower. This means the XM174 can be installed on land vehicles as well as aircraft such as attack helicopters.

In both cases, the system provided substantial long-range firepower, although the ammunition supply was fairly limited. The XM174 is one such weapon that can be used both offensively and defensively, allowing for greater tactical flexibility.

Members of the U.S. Army, U.S. Marine Corps, and U.S. Air Force Security Police all assessed service types. Throughout the war, the 40mm M79 single-shot burst grenade launcher proved to be the standard for the U.S. military.

Other development alternatives have been released, although none are officially accepted in number. The M79 eventually became the 40mm M203 today, and the automatic grenade launcher system became the belted Saco Defense Mk 19 first deployed in 1968.

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