Grenades and Firearms: Under Barrel Grenade Launchers

In our last two posts, we studied two different ways to couple grenades with firearms, namely rifle grenades and shoulder fired grenade launchers. Rifle grenades have good range and can be used along with a rifle, but the user cannot simultaneously use it as a rifle and a grenade launcher. Shoulder fired grenade launchers also have very good range, but the user can only use it as a grenade launcher and has to have a small side arm as a backup weapon. The next type of coupling grenades with firearms is the most common one today: the under barrel grenade launcher. We will study them in this post.

Grenade launchers generally tend to have shorter barrels and lower barrel pressures, so it is possible to eliminate the butt stock of a shoulder fired grenade launcher and attach the rest of the parts to the underside of a rifle barrel.

Public domain image of an M4 fitted with an under barrel M203 grenade launcher

In the image above, we have a M203 grenade launcher attached underneath the barrel of an M4 assault rifle. Note that the grenade launcher has its own trigger which is located in front of the M4's magazine. It also has its own adjustable leaf sight, which is the long thin rod in front of the telescopic sight. The leaf sight is used in conjunction with the M4's front sight to launch grenades.

Public domain image of a US soldier using a M203 under barrel grenade launcher attached to the underneath of a M16 assault rifle.

Note how the soldier is using the leaf sight along with the M16's front sight to aim the launcher.

Western made under barrel grenade launchers typically are loaded from the back and the launcher tube either pivots to one side or slides forward to allow the user to load a new grenade cartridge. Russian made grenade launchers are usually loaded from the muzzle.

To launch the grenade, the user typically shifts their hand that is on the rifle's pistol grip to the magazine and then pulls the grenade launcher's trigger. To go back to shooting the rifle, the user simply moves his/her hand back to the pistol grip.

Since the butt stock is shared between the rifle and grenade launcher, this design is much lighter than carrying a rifle and a separate shoulder fired grenade launcher. Unlike rifle fired grenade launchers, the user can walk around with a magazine loaded in the rifle and a grenade cartridge loaded in the launcher and use either at a moment's notice. The user can also easily switch between the two as needed. There are a few disadvantages with this type of launcher though. The first is that the attached grenade launcher alters the balance of the rifle. The second is that these usually don't have as much range as a rifle grenade launcher or a shoulder fired grenade launcher. The third is that these are single shot devices and the user needs to manually reload after each cartridge is fired.

Models such as the US made M203, the German AG36 and the Russian GP-25 and GP-30 are some common under barrel grenade launchers used around the world.

Grenades and Firearms: Shoulder Fired Grenade

In our last post, we studied some early developments in grenade launching technology, i.e. the rifle grenade. One of the features of the rifle grenade is that it is built to be used with a normal infantry rifle and some sort of adapter. The user can switch between using the rifle and using it as a grenade launcher. In this article, we will study dedicated grenade launching firearms i.e. devices that are only meant to launch grenades and cannot be used as a rifle.

During the Vietnam war era, the US military developed a dedicated shoulder fired grenade launcher called the M79 for use by troops. The plan was to design a weapon to increase the firepower of troops, while having more accuracy than a rifle grenade, but lighter than a mortar. As a result of this research, the M79 grenade launcher was developed.

M79 grenade launcher. Click on image to enlarge. Public domain image.

It is a simple design that resembles a break-open action shotgun. The front sight at the very end of the muzzle is a fixed type and the rear sight (which is mounted midway on the barrel) is a folding leaf sight.

Even though the original requirement was for a multi-shot launcher, the designers never got that to work reliably and the weapon is a single shot one. This means the user needs to manually load a new cartridge after each shot. This weapon has a range of 75 to 375 meters and can fire a variety of grenade types. It was delivered to the US army in 1961 and quickly became popular among the soldiers, due to its reliability and simplicity. They called it by various names, "Blooper", "Thumper", "Thump-tube" (all due to the sound that it made), "Wombat" (this was its Australian nickname) were all common names. The downside of it was that it was a single-shot weapon and could not shoot rapidly. It also had the problem of being a dedicated device, so the soldier carrying one would only have a small pistol to defend himself.

The South Africans developed a multi-shot dedicated grenade launcher called the MGL. This was developed during 1980-1981 and adopted by their military in 1983. Soon after, it was adopted by other military forces around the world. In US military service, it is called the M32.

US Marine using a M32 multi-shot grenade launcher. Public domain image.

It consists of a six shot cylindrical magazine that resembles a revolver magazine. One major difference though is that the magazine is driven by a spring, so it must be wound back up after reloading. This fires a variety of grenades, just like the M79 does. In fact, one variant is the same caliber as the M79.

In the next post, we will look at some other types of launchers as well.

Grenades and Firearms: Rifle Grenade

In our last post, we studied the origins of the grenade and about those specialized troops trained to use them, the Grenadiers. Towards the end of the last post, we'd mentioned that grenadiers and grenades started to become less useful towards the end of the 19th century, but grenades came back in popularity in the 20th century. We will continue our story from here.

In 1904, as relations between the Russian empire and the Japanese empire broke down, the Russo-Japanese war began. This was the first major war in the 20th century and had modernized troops on both sides. A Japanese colonel named Amazawa started experimenting with grenades fired out of rifles, during the Battle of Port Arthur. In our previous post, we'd mentioned that grenadiers of the previous era were typically the largest and strongest soldiers because they needed to throw the grenade for a considerable distance. A rifle fired grenade made it possible for weaker soldiers to use grenades too, by using a firearm to launch the grenade instead of throwing it.

The idea of using a firearm to launch a grenade is actually an old invention and was not of Japanese origin. In the School of Infantry Museum in Warminster, England, there is a flintlock musket called the "Tinker's Mortar", which dates back from 1681. This unusual musket has a cup built into the buttstock. To use it as a launcher, the user would first place the rifle with the muzzle on the ground, then pour a propellant charge into a special chamber under the the cup. A channel ran from the flintlock pan to the cup. A grenade with a fuse was placed inside the cup. When the powder in the pan was lit, the pressure of the burning propellant would launch the grenade and the flash would also simultaneously light the fuse as the grenade was pushed out. This was a very cumbersome device, so the idea of a rifle launched grenade was generally shelved in the west for a few centuries. It was the work of Colonel Amazawa in Japan that restarted interest in this subject again. As it turned out, a number of observers from every major western power were watching the course of events of the Russo Japanese war and this is how the concept returned back to Europe.

In 1907, a Britisher named Martin Hale invented a rod grenade, followed by other inventors with similar ideas from Germany, France, Austria etc.

A Mills bomb Number 23 Mk 1 rod grenade. 

Image licensed under Creative Commons Attribution-Share Alike 3.0 Unported license by Jean-Louis Dubois

The concept of a  rod grenade is simple. It consists of a specialized grenade with a simple steel rod attached to it. The rod is inserted into the barrel of the rifle and a special blank cartridge is chambered into it. The rifle butt is placed on the ground. The user holds the grenade's safety spoon with one hand and removes the safety pin with the other. The user then places the hand that removed the safety pin back on the rifle's grip, then released the hand holding the safety spoon and places it on the fore stock and fires the rifle as quickly as possible.

This idea was used from 1907 to the early stages of World War I. While it worked decently in theory, there were some practical issues with it. On the good side, it enabled users to launch grenades at longer distances than was possible before. However, after repeated firing of grenades with this method, the rods tended to damage the rifle's barrel. If the user didn't move fast enough after releasing the safety spoon, the grenade could end up exploding on the user's face. If the user was suddenly faced by an enemy close by, the rifle was unusable as a firearm, as the user would have to remove the grenade from the muzzle, re-insert the safety pin back into the grenade, remove the blank cartridge and then chamber a normal round before he could use the rifle to shoot at his enemy.

In order to fix the issue with the rods damaging barrels and the need for the user to quickly launch the grenade after releasing the safety spoon, a cup-type rifle grenade launcher was invented in the middle of World War I. With this, a standard hand grenade could be used. The user would remove the safety pin and place the grenade in the cup launcher. The cup held the grenade's safety spoon in place until it was launched. The user would then place the rifle butt on the ground, load the rifle with a special blank cartridge and then fire it. This type did not wear out the barrel like the rod grenades did and also, the user didn't have to fire the weapon right away, as the cup would hold the grenade's safety spoon in place until it was fired. It also could use standard hand grenades, which meant the soldier didn't need to carry two types. The only disadvantages are that it required the user to use a special cup adapter and a special blank cartridge to shoot grenades, which could leave the user vulnerable if he was surprised by an enemy when preparing to fire one.

The next development was by the French and was called the "Vivien et Bessiers" shoot-through grenade named after its inventors, Vivien and Bessiers, (otherwise called VB grenade). This built on the concepts of the cup-type rifle grenade, but did not require a special blank cartridge to launch. Instead, this type of grenade has a hole in the middle, that allows a standard rifle bullet to pass through it. As the bullet passes through the center, it arms the grenade. The grenade is then launched by the hot expanding gases coming out of the barrel. So all that the user has to do is place the grenade on the cup and then use a standard rifle bullet to launch it. While this type did not require special blank cartridges, it still required a special cup adapter to use.

Another type of grenade is the bullet-trap type, which traps the bullet instead of letting it pass through and uses its momentum to carry the grenade into the air. Like the shoot-through grenades, the user can use a normal cartridge to launch the grenade and has no need to carry blank cartridges. This type does not require any special cup adapter unlike the shoot-through type.

A French APAV40 grenade (green) at the end of a FAMAS rifle. Click on image to enlarge

Original file was licensed under a Creative Commons Attribution-Share Alike 2.0 license by Rama at wikipedia.

In the above picture, we have a bullet-trap type French APAV40 rifle grenade (the green part). This can be used for both anti-personnel and anti-vehicle applications. The user merely places it on the muzzle of any NATO rifle (such as the French FAMAS rifle) and pulls the trigger. The impact of the bullet striking the bullet trap and the expanding gases serve to arm the grenade and launch it in the air. The grenade has a mechanism that allows it to explode on impact. Larger bullet trap types such as the French AC58, the Belgian & Leichtenstein ENERGA grenade and the American M31 HEAT were designed to be used against armored vehicles.

Rifle grenades have the advantage of having the maximum range of all firearm launched types and modern designs do not require any special adapter or ammunition to launch them. Also, the rifle's balance and weight are not affected as some other designs which we will study shortly. The disadvantage is that if the user wants to launch a grenade, he must mount it to the muzzle before every shot. If he is surprised by an enemy at close range while preparing to fire a grenade, he cannot easily respond with his rifle, as it takes some time to take out the grenade and prepare the rifle to shoot normally.

In our next post, we will study some more developments of using firearms to launch grenades, including dedicated grenade launchers.

Grenades and Firearms: Basic History

A grenade is a weapon with a long history and in recent years, it has been combined with firearms to produce rifle-launched grenades, under barrel launchers etc. We will study how this came to be in the next series of posts.

The word "grenade" is based on the French word for the pomegranate fruit, as some early grenades used to have the same basic shape as the fruit and the shrapnel inside resembled the seeds of a pomegranate.

It may come as a surprise to some to discover that grenades were in use before the invention of gunpowder! The very first grenades were clay pots that were filled with incendiary material such as petroleum and Greek fire (the method and ingredients for making Greek fire were closely guarded state secrets and the formula has now been forgotten, but we know from ancient historical documents that it was a very flammable liquid and could continue to burn on top of water.) These grenades first appeared on the scene in the Eastern Roman empire (i.e. Byzantine empire) around 740 AD or so. Later on, glass containers were also used instead of clay pots.

Ancient Grenades. Click on image to enlarge.

Image licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License by user badseed at Wikipedia.

People would fill containers like these with petroleum or Greek fire, seal the hole on top and then tie a burning rag and throw them. Upon hitting a hard surface, the container would shatter and spill its contents around an area and the contents would then ignite from the flame on the burning rag, thereby causing havoc over a small area. This idea later spread to Muslim areas during the crusades and from there on, it worked its way into China by the 10th century AD.

Meanwhile, the Chinese had also discovered gunpowder at around the same time and soon after, they began packing it into their grenades. A military manual called Wujing Zongyao ("A Compilation of Military Classics") written in 1044 AD describes a gunpowder recipe to be used with a grenade. About three hundred years later, the Chinese began to make their grenade shells out of cast iron rather than clay or glass for greater effect. This was mentioned in the Chinese Song dynasty era book Huolongjing ("Fire Dragon Manual") written in the 14th century, which describes various gunpowder based weapons in use in China during that period. One of the formulas that the author recommends is a mixture of tung oil, urine, sal ammoniac, feces and scallion juice to be heated and then coated upon tiny iron pellets and bits of broken porcelain. The pellets are then put in a cast-iron container loaded with gunpowder and then launched either by hand or catapult. Anyone unlucky enough to be hit by this shrapnel would die slowly from blood poisoning, if they were not killed outright.

The cast-iron and gunpowder design slowly started to move back westwards from China to Europe and in the 17th century, European countries were using cast-iron gunpowder based grenades as well. The word "grenade" to describe the weapon was first recorded in use in 1688 during the Glorious Revolution, though it is possible that they were in use in Europe some decades before in Austria and Spain.

As the Europeans began to use the grenade, they also developed specialized troops trained to use these weapons. Such troops were called "Grenadiers" and the first official grenadiers were in the army of King Louis XIV of France.

A grenadier belonging to Emperor Napoleon's guard. Click on image to enlarge. Public domain image.

Since a grenade lays damage about a large area, it was necessary for a grenadier to be able to throw it far away as possible in the direction of the enemy and away from one's own troops. This meant that the grenadier had to be a person who was taller and stronger than average. A grenadier also had to be brave and disciplined enough to stand up in the front of the line, light the fuse of his grenade, wait for the fuse to burn down and then throw it at an appropriate time so that the enemy could not throw it back. Only the largest and strongest soldiers were chosen as grenadiers and they were given more training than the average soldier. The grenadiers were therefore regarded as the elite assault troops of their era and had higher pay and wore special uniforms to show their status.

By the 19th century, the use of grenadiers to throw grenades had become less useful, but such large imposing soldiers were also used to lead dangerous assaults on the battlefield.

The revival of grenades in warfare and using firearms to launch them (so that weak people could also launch them for a longer distance easily) began with the Japanese in 1904, but that is a subject for the next chapter, where we will study how firearms and grenades started to become integrated.