XM174 automatic grenade launcher (USA)

Since the early sixties, US gunsmiths have been proposing new designs of automatic grenade launchers, including those intended for use by infantry or crews of armored vehicles. Some developments of this kind did not cope with all the necessary tests and were put into service. One of the "losers" of that time can be considered an XM174 grenade launcher. He coped with the testing ground, but did not justify himself in a real armed conflict.

In 1964, the US Military Assistance Command, Vietnam or MACV ordered the industry to develop a new automatic grenade launcher. The military wanted a system capable of increasing the firepower of the unit and supplementing the existing machine guns. The grenade launcher was to be mounted on a portable machine or mounted on a vehicle. First of all, he was considered as a means of self-defense of convoys that risked ambush. However, other uses were not excluded. weapons.

XM174 automatic grenade launcher (USA)
Major J. Flynn from the 26 regiment of the KMP demonstrates the XM174 grenade launcher to the representatives of the command, October 30 1969. Photo Wikimedia Commons

For a number of reasons, the development of new samples for MACV was seriously delayed. The requirements for a prospective grenade launcher were formed back in the 1964 year, but the real start to the full-fledged project was given only in the early spring of the 1966. It took another two years to complete the design work, assembly, and factory testing of several samples. Only in May 1968, the army was able to conduct a comparative test of the four grenade launchers presented and draw conclusions.

For comparative tests of 1968, four new grenade launchers from different developers were launched right away. One of the projects was proposed by Aerojet, which already had experience in creating modern weapons. Her version of the promising grenade launcher received the working designation XM174. It is worth noting that later this grenade launcher was able to reach military trials, but he did not manage to enter service. In this regard, he stayed in stories under the working title and did not lose the letter "X".

General view of the XM174 product. Photo from the book "The Machine Gun"

Probably, the designers from Aerojet knew about other automatic grenade launchers of that time, and also took into account their main drawbacks. This is what explains the fact that XM174 was markedly different from some other early samples. However, the project did not go without borrowing and rethinking already known ideas. So, one of the “sources of inspiration” for gunsmiths was the machine gun M1919. This product borrowed some layout solutions and certain ideas in the field of automation.

The XM174 grenade launcher differed from other samples in its rather simple appearance. He received a rectangular receiver on which the fixed barrel and the side tray-receiver of the store were fixed. A pistol grip of fire control was placed on the back wall of the box, similar to the M1919 machine gun. The weapon was supposed to use automatics based on the rollback of the free shutter. The project provided for the possibility of firing single and queuing.

Scheme grenade launcher. Picture from the book "The Machine Gun"

All the main parts of the automation were placed inside a rectangular receiver, divided into a couple of parts. In this case, the top cover, connected to the main box with the help of a front hinge, was larger. In the front of the box there were attachments for the barrel, placed inside the smaller casing. On the left side, there were devices for fastening the store, opposite of which, on the right, there was a window for ejection of cartridges. The entire rear part of the box was given for the installation of a shutter with a return spring and a trigger mechanism.

Grenade equipped rifled barrel caliber 40 mm. The barrel chamber was designed for a shot of type 40х46 mm. Unlike a number of other automatic grenade launchers of that period, the barrel was rigidly fixed in its place and should not have moved when fired or reloaded. In particular, this allowed the use of the barrel for the installation of sights.

Principles of interaction between the gate and the grenade delivery system. Picture from the book "The Machine Gun"

XM174 received automatics based on a free shutter. A movable valve with a rectangular cross section was placed in the receiver. In its front part there was a cup with an extractor, and along the axis a channel for a spring-loaded drummer passed. Behind the shutter was supported by a powerful return spring. On different sides of the shutter there were stops and hooks to interact with different devices. So, during a rollback and moving forward, he had to cock the trigger and also transfer energy to the shot delivery system. Due to the correct selection of the gate mass and the characteristics of the spring, it was possible to reduce the rollback speed and due to it to get an acceptable recoil force.

Details of the hammer-type firing mechanism were placed both in the rear part of the receiver and directly in the gate. Fire control was carried out using the trigger on the hilt. There was also a fuse-translator of fire. The design of the trigger ensured the fire bursts or single.

The XM174 project provided for the use of store ammunition uncharacteristic for automatic grenade launchers of that and later time. Shots such as 40x46 mm were proposed to be placed in a special shop, mounted on the weapon on the left. The store had an oval-shaped case with flat covers. Inside it was a supply system of ammunition with its own spring. The store was 27,3 wide cm and height 14 cm managed to fit 12 grenades. With the help of the latch of the lower location, the magazine was to be mounted on the side tray-receiver of the grenade launcher.

Trigger mechanism. Picture from the book "The Machine Gun"

The mechanics of the store provided only the supply of a grenade to the weapon. Its transfer to the line of unloading was carried out by its own grenade launcher system. In the receiver tray was a movable feeder, mechanically connected to the shutter. When the latter rolled back, he had to shift to the right, dragging a grenade behind him, while rolling back - to return to the starting position and catch the next shot.

The grenade launcher received sights borrowed from the M79 serial product. Directly on the muzzle of the trunk was a fly with side protection. At some distance from it with the help of a collar mounted frame sight with a fully mobile. In the stowed position, he leaned forward and lay on the trunk. Such a sight allowed to fire at distances of no more than 400-500 m, which corresponded to the parameters of a grenade.

Designers from Aerojet equipped their grenade launcher with a pistol grip with the rear, with which it could be held and guided. On the bottom of the receiver, they provided a mount for mounting on a standard tripod machine. Carry weapons offered using a conventional belt. To install it on the cover of the receiver placed a pair of swivels. As planned by the gunsmiths, the calculation of two people could easily carry the grenade launcher, the machine tool and several shops with dozens of grenades. In this case, the weapon could be installed on any suitable vehicle, which sharply increased its mobility.

Shop on 12 grenades. Picture from the book "The Machine Gun"

The total length of the XM174 product was 28 inches (711 mm), the width with the magazine receiver and the shutter handle was 8,625 inches (220 mm), and the width with the magazine was 15,25 inches (387 mm). The height of the weapon without a magazine is 6,25 inches (159 mm), with the magazine is 8,5 inches (216 mm). The grenade body weighed just 16 pounds (7,26 kg). Shop with 12 grenades - 10 pounds (4,5 kg). The technical rate of fire, according to calculations, reached 350 shots per minute. Effective fire range - no more than 350-400 m.

Before firing, the grenade thrower should have installed a magazine in the receiver, and then cocked the weapon with the help of the bolt handle, moving it back and returning it to its original position. Then you could turn off the fuse, select the fire mode and press the trigger. The latter, when pressed, released the trigger that struck the drummer. Under the influence of recoil energy, the shutter began to roll back, removed and threw an empty sleeve to the right. When rolling back, he cocked the trigger and also forced the ammunition system to draw a new shot inside the receiver. Then the return spring brought him to the starting position, sending a new grenade, and the shooter could take the next shot.

One of the XM174 grenade launchers during tests in Vietnam. Photo by Airwarvietnam.com

In May, several automatic grenade launchers from various developers, including the Aerojet XM1968, were presented to the joint test 174 of the year. The latter passed all the necessary checks and, despite the minor remarks of specialists, it showed itself well. After small improvements aimed at getting rid of minor shortcomings, such a weapon could well get into the army.

XM174 fully confirmed the design characteristics, both technical and operational. In addition, new weapon capabilities were found. The grenade launcher with the magazine weighed less than 12 kg, and besides, it had a rather low return. In practice, it was found that an experienced rocket launcher can shoot him not only from the machine, but also from the hip. However, in this case it was not necessary to speak about the accuracy and efficiency of the fire.

According to the results of ground tests, a new automatic grenade launcher was allowed to check in the troops. Soon, an experimental batch of ten items was handed over to the army and immediately went to Vietnam. The weapons were supposed to be tested in the conditions of a real war, and based on the results of such an inspection, to make a final decision. In the case of a positive outcome of military tests XM174 in the near future could enter service and go into the series.

Fighters master new weapons. Photo Nam-valka.cz

The grenade throwers involved in the tests quickly enough confirmed all the previously established advantages of the new weapon. But at the same time they found several new flaws. It turned out that a small mass of weapons is not a decisive advantage, and it can be implemented by no means in all conditions. For example, when installing weapons on a vehicle, its mass ceased to play a significant role. A grenade ready for firing at the 12 was considered insufficient. At the same time, regular stores were not very strong and constantly broke down.

It should be noted that at the same time other new samples were tested in Vietnam. Like XM174, they showed not only positive, but also negative qualities. In the course of military tests, voluminous reports were prepared with descriptions of individual samples and their comparative analysis. In general, the Aerojet grenade launcher did not have any decisive advantages over its competitors, but it was not inferior to them in its basic characteristics. At the same time, various drawbacks seriously hampered the operation of all submitted samples. Only experienced Mk 19 grenade launchers positively stood out against other products.

In 1968-69, the command of the American army examined the results of ground and military tests of a new weapon, and soon made its decision. The existing XM174 product from Aerojet was considered unsuitable for adoption and serialization. The military decided to limit the first experimental batch of 10 weapons. These products have already been used in Vietnam, and they have decided to leave them to the parts that previously carried out the tests.

Ways of mounting a XM174 grenade launcher. Medium.com Photos

According to various sources, the XM174 grenade launchers remained in operation for the next few years. They were mainly used for the defense of stationary objects. Apparently, from time to time this “group” suffered losses, both from enemy fire and due to technical factors. Not later than the mid-seventies, the last of the available grenade launchers was written off. None of the released XM174 has been preserved.

By the end of the sixties, American industry had developed a number of promising automatic grenade launchers for various purposes and, as expected, not all of them were able to go into service. In particular, the product XM174, having some positive qualities, was not strong enough for actual operation, and also had other drawbacks. In this form, it could not go into service, especially considering that at the same time there was a much more successful grenade launcher Mk 19. A small batch of XM174 grenade launchers failed to exert any influence on the rearmament of the troops, but the engineers and the military were able to assess the real possibilities and prospects of the proposed design. This was probably the main result of the Aerojet project.

Based on:
Chinn GM The Machine Gun, Vol. Five. 1987.
Karpenko A.V. Automatic grenade launchers - weapons of the XX century. M .: Zeihgauz, 2007.
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  1. -1
    10 November 2018 06: 59
    Grenades from automatic grenade launchers, as well as grenade launchers, have one significant drawback ... the small breakdown power of the fragments, this is due to their small mass ... The rubberized army cloak protects them well ...
    1. +1
      10 November 2018 07: 31
      Quote: Vard
      An army rubberized coat protects them well ...

      have you tried?
      1. +2
        10 November 2018 08: 49
        Yes ... Dress him for a scarecrow ... For cotton pants and a pea jacket ... There was no through penetration ...
        1. +1
          10 November 2018 09: 09
          I wouldn’t think ... So weak? So, in winter clothes, shelling from such is not terrible ... wassat
        2. +1
          10 November 2018 09: 58
          If they set for 100 meters, then yes, it won’t penetrate, but I shot from the Mk19A3 AG, so its grenades have a radius of the zone of continuous destruction with ready-made fragmentation elements - 5 meters, and so reinforced concrete is crumbled, my mother does not worry.
        3. +1
          10 November 2018 14: 49
          Quote: Vard
          Yes ... Dress him for a scarecrow ... For cotton pants and a pea jacket ... There was no through penetration ...

          On a stuffed animal is not a check.
          Weight and hardness are not like those of the body.
          The energy of the fragment passes into the kinetic energy of a stuffed animal
    2. +2
      10 November 2018 22: 47
      I don’t know which grenade is described here, but if it’s VOG 17, then about the cloak is nonsense, the fragments from the VOG-17 shot calmly pierce the SS 68 helmet three four meters from the place of the grenade explosion, and the only drawback of VOG17 is its small radius of destruction of 7- 10 meters and flies for a very long time at 700-800 meters flies in 5-6 seconds, if not more.