Modern Firearms - Grenade launchers - Rifle, Underbarrel, Antitank

Basically, the grenade launcher is a weapon which fires a grenade – a small shell, filled with high explosive or other agent, such as tear gas for less lethal application, bright burning compound for illumination purposes, incendiary filling etc. Of course, in most cases the grenade also must be fitted with a fuse, and with a safety, to avoid damage to the grenadier or handler. The simplest way to use the grenade is to throw it by hand; but the effective range and maximum weight of hand grenades is severely limited; so, at the earliest stages of the development of firearms, many armies used so called “hand mortars” – basically, the smoothbore muskets with short barrel of very large caliber, which was used to fire standard grenades at ranges beyond the limits of human throwing ability. During the First World War most nations started to use so called “rifle grenade launchers”. These launchers in fact were add-ons to standard issue military rifles, usually in the shape of a cup, attached to the muzzle of the rifle. A grenade was placed into this cup, primed, the rifle aimed toward the enemy, and then the grenade was launched using a special blank cartridge. This system, while enhancing the combat capabilities of infantry soldiers, has several drawbacks – for example in many cases the attached launching cup blocked the line of sight for the rifle.

German Mauser K98k carbine (WW2 period) with attached cup-shaped grenade launcher

There was another type of rifle grenade, which did not require any attachment to the rifle – instead, this system relied on a special thin rod, attached to a grenade as a tail. This rod was inserted into the bore of the rifle, and the grenade was launched using a blank cartridge. In either case, an attempt to fire the grenade with a standard round of riffle ammunition was disastrous to both weapon and the shooter. Most modern rifle grenade launchers got rid of both the cup launchers and rods attached to the grenade. Instead, these are just specially shaped muzzle devices, often also combined with flash hiders; the tail (rear) part of the grenade is shaped as a tube, which is slipped over the muzzle of the rifle. Also, most modern types of rifle grenade launchers use standard ammunition, and either trap the bullet and use its energy to project the grenade (helpfully known as the 'bullet trap' type) or have a hole down the center through which the bullet escapes (the 'bullet through' type), and use the gun gas expanding from the muzzle as a propellant. The latter loses something in energy, but gains through not having to switch the gas operation valve to 'closed' first.
The key problem with a rifle grenade is that when ready to fire, it effectively blocks the standard operation of the rifle. That means that if the shooter with a grenade in place has to fire his rifle in an emergency (e.g., if an enemy pops out in front of him), he should first either remove or launch the grenade, which will take time and may cost him his life.

French soldier aims with the rifle grenade, mounted to the barrel of the FAMAS assault rifle

Modern Yugoslavian rifle grenade, ready to be fired from the muzzle of Zastava M70 assault rifle

To solve this problem, many countries developed and adopted so called “underbarrel grenade launchers”. Unlike the rifle grenade launchers, which are just attachments to the standard rifle, an underbarrel launcher is a complete weapon, with its own barrel, trigger / firing unit, safety, and often its own sights. The infantry [assault] rifle is used only as a host firearm, providing the stock for the grenade launcher. First developed between the wars in Italy and Japan, the underbarrel launchers appeared in their modern shape in the late 1960s, both in the USA and in the USSR. The underbarrel launchers do not block the rifle, but add a significant penalty in the bulk and weight of the combined weapon. Also, typical grenades for underbarrel launchers have warheads much smaller in size and weight, limiting their effectiveness against the targets (but increasing the number of grenades a soldier can carry with him).

American soldier aims with the M4 carbine, combined with M203 underbarrel grenade launcher	a variety of 40mm grenades for NATO-standard grenade launchers
Soviet-made AK-74 assault rifle with GP-25 40mm underbarrel grenade launcher

The actual choice of the type of grenade launcher varies – some countries, most notably the USA and the former USSR/Russia, stuck completely with underbarrel grenade launchers, some others, like Belgium or France, seemed to prefer rifle launcher type, while many other countries, such as Germany, produced both types of weapon,.
The post-war period saw a short period of renaissance of the stand-alone grenade launchers, similar in basic idea to the “hand mortars” mentioned above. First these were re-introduced in service by the Germans during WW2, as the “kampfpistole” – a modified flare launcher, fitted with a rifled barrel and a detachable shoulder stock, and firing various types of grenades. In the postwar period, several countries developed single-shot, shoulder-fired grenade launchers, usually of 40mm caliber, which actually preceded the modern underbarrel grenade launchers and used the same types of ammunition. The most famous of these is probably the US M79 “thumper”, widely used during the Vietnam War. The key problem with these weapons was that they required the grenadier to carry some sort of personal defense firearm in addition to the grenade launcher, such as a pistol, submachine gun or rifle. Latter on, several countries produced multi-shot versions of stand-alone shoulder fired grenade launchers, usually in the form of a large revolver, or a pump-operated rifle with a tubular magazine. Military users mostly replaced these weapons with underbarrel grenade launchers, and stand-alone launchers are mostly used either by special operations forces or by police forces, which employ the launchers for less-lethal anti-riot applications, firing tear gas canisters and baton rounds (rubber projectiles or buckshot).

German HK69 40mm single-shot grenade launcher Image: www.autoweapons.com	Russian GM-94 43mm multi-shot grenade launcher (with tubular magazine above the barrel) Image: www.shipunov.com
Drawing of a future multi-shot 40mm SAAB-Bofors AGR grenade launcher with computerized sight and time-fuzed grenades

The most recent trend in this field is the development of time-fuzed grenades in conjunction with a fire control computer, mounted on the rifle and coupled with the sights. This unit incorporates a laser rangefinder, a ballistic computer and a means for programming the warhead before the shot. Before firing, the shooter determines the range to the target using the laser rangefinder, and the computer automatically corrects the sights to achieve the appropriate trajectory and presets the time fuze, so the warhead will explode when it reaches the target. This allows the engagement of targets 'in defilade' (i.e. when they are hiding behind cover) by using air-burst fragmentation warheads. At the present time there are several projects that attempt to achieve such an effect, including the American XM-29 OICW system and French PAPOP. The Belgian F2000GL system offers a less costly alternative, with non-programmable grenades but with an electronic sighting unit which allows much more accurate long-range fire.
The key targets for rifle and underbarrel grenade launchers are enemy targets of the “soft” type – infantry, light entrenchments, unarmored or lightly armored vehicles etc. Most tanks developed during the Second World War and since are usually far too strong to be disabled with the relatively small amount of explosive carried in a typical grenade.

Automatic grenade launchers

US troops with Mk.19 mod.3 automatic grenade launcher

It is generally believed that first automatic grenade launchers were developed in USA by mid-1960s, following the US involvement in the Vietnam war. These weapons were developed by US Navy and several military contractors to provide troops with close to medium range support and area suppression weapons, effective against enemy infantry and light structures. These weapons were light and compact enough to be installed on riverine crafts, combat helicopters, jeeps, and on light infantry mounts (tripods). What is generally not known is the fact that very similar weapons were developed and tested in USSR prior to WW2, in around 1935-38. There were several designs of such weapons, but most developed of these was the 40,6mm automatic grenade launcher designed by Taubin. This magazine-fed, selective fired weapon was developed as a more versatile alternative to the 50mm mortar; it fired 40,6mm fragmentation grenade (based on standard issue 40,6mm Dyakonov rifle grenade M1930) in either direct and indirect fire modes. However, changes in General Staff of Red Army following Stalin's repressions of 1937-39 resulted in withdrawal of Army support to this project, and Taubin grenade launcher never went past prototype stages. The Taubin itself has been arrested, tried on false accusations, found guilty and later executed.

Soviet Taubin 40,6mm automatic grenade launcher on field trials, circa 1938

Two view drawing of American Mk.18 mod.0 grenade launcher (1962), one of the first such weapons to be developed and used in combat in S-E Asia. Unlike most successors, this was not truly automatic, as it fired via hand-crank located at the right side of the receiver

For several decades the automatic grenade launcher concept in USSR was completely suppressed by light mortar concept, and it was Vietnam war that brought these weapons back to consideration of Soviet army. Soviet Army got its new automatic grenade launchers in about five years later than Americans; while Soviet and Russian 30mm weapons are somewhat less versatile because of narrower selection of available ammunition types, these weapons also significantly lighter than their Western counterparts. During 1980s and 1990s, several other nations began to develop and manufacture their own grenade launchers, chambered either for NATO-standard 40mm High Velocity ammunition of US origin, or for 30mm Soviet ammunition. However, by late 1980s Chinese developed their own grenade ammunition of 35mm caliber, and later produced a lightweight, one man-portable weapon of indigenous design. This launcher, initially known as W87, is very mobile but lacks suppressive firepower because of smaller capacity magazines (maximum magazine capacity 12 or 15 rounds as opposed to 30 to 40 round belt capacity of Soviet and Western weapons).

Chinese soldier fires an early version of the 35mm W87 automatic grenade launcher, fitted with drum magazine

40mm CIS 40GL automatic grenade launcher, made in Singapore; it is installed on some infantry combat vehicle

Current grenade launchers usually provide both direct and indirect fire capabilities with maximum effective range against point targets being about 800 to 1500 meters, and maximum possible range against area targets up to 2200 meters. Typical anti-personnel grenade weights around 250 g (complete round weight usually about 300 g, muzzle velocity about 180 to 240 m/s); such grenade carries about 30 g of high explosive and provides kill zone with radius of up to 5-7 meters (damage zone radius up to 15 meters). Grenade launchers in turn usually represent large belt-fed machine guns with short, stubby barrels with caliber between 30 and 40mm, mounted on tripods or various vehicle mounts. Typical rate of fire for automatic grenade launchers ranges from 100 to 400 rounds per minute. Not surprisingly, such weapons can provide formidable suppressive or target disabling fire against infantry and light vehicles and structures. Other than anti-personnel, fragmentation ammunition, many countries also produce armor piercing ammunition for use against enemy's armored personnel carriers and trucks (typical penetration is about 5 cm / 2 inch of steel armor), dual purpose (fragmentation - AP), short range shrapnel and other types of rounds.
The most recent trend in development of automatic grenade launchers is to provide these weapons with computerized sights, that can measure range to the intended target and provide operator with necessary aiming information, either for direct or indirect fire. Further development is concentrated on air-bursting warheads that can be set up automatically to explode over the heads of enemy personnel ad desired range (also provided automatically from laser range-finder via computer sight). Several countries currently are developing such ammunition and fire control units for 40mm weapons (those include at least Norway, Singapore and USA) and at least one country develops same concept in smaller 25mm caliber (USA).

Antitank grenade launchers.

German Panzerfaust grenade launcher of WW2 era

Soldier aims with the Soviet RPG-7 grenade launcher

Most antitank grenade launchers are separate shoulder-fired recoilless weapons, which typically consist of a smoothbore barrel, opened at both ends, a firing module with trigger, safety and ignition unit, and some sort of sights. The grenades are divided into three major types – RCLs, rockets, and dual mode (RCL+rocket). The RCL grenades are launched using a propellant charge, which is placed inside the barrel behind the grenade; as the barrel is open at both ends, some (actually most) of the propellant gases are ejected to the rear, effectively countering the recoil. The negative side of this system is the backblast, with the danger zone being as big as 20+ meters beyond the launcher. To minimize this problem, some variants (e.g. the German Panzerfaust 3) instead eject powder or fiber material at high velocity rearwards, thereby reverting to the original countermass form of the recoilless gun invented by Cleland Davies before WW1. The rocket grenades use a small rocket motor, attached to the grenade; sometimes this rocket burns out completely within the launcher tube, sometimes it continues to burn longer. In the latter case, the shooter must be protected from the rocket blast by some special means, such as a protective shield. The third, dual mode, system combines both principles, using the small RCL charge to launch the grenade from the tube; then, at the safe distance (usually about 10 to 30 meters) the rocket motor ignites, and further accelerates the grenade, greatly increasing the effective range. Obviously, the antitank grenade launchers are very simple and inexpensive; the most complex part of the system is the grenade (or, rather, the development of the effective grenade is quite complex and expensive – the production is quite simple), and, in most modern systems, the sights. The earliest or most simple launchers usually had open sights with some sort of scale for different ranges. Since the late 1960s, some grenade launchers (most notably the RPG-7) are fitted with more effective optical sights, with range-finding scales and complex aiming reticules. The most recent developments in electronics and lasers involve computerized sights with laser rangefinders and automatic aiming correction.
Early grenades used relatively simple warheads filled with standard explosives like TNT; modern warheads, designed to defeat the extra-thick composite armour of modern battle tanks, often further enhanced with ERA (explosive reactive armour), use dual warheads, filled with complex and highly effective explosives. In the dual warhead systems, a front warhead of smaller size is used to set off the ERA, and then a larger second warhead strikes the hull of the tank.
To further extend the usability of antitank launchers, the HEAT grenades are often complemented with warheads of other types, such as HE-FRAG (High Explosive-Fragmentation) for anti-personnel use, Incendiary, Thermobaric/FAE (Fuel-Air Explosive, used against soft targets, bunkers and personnel in the open or in defilade), smoke and some others.
It must be noted that only the most powerful antitank grenades can defeat the modern battle tank from the front. However, armor on the sides and on the rear of most tanks is much thinner, and thus much more vulnerable to the “poor man’s antitank artillery” – the antitank grenade launcher. The recent campaigns of the US army in Iraq and of the Russian army in Chechnya proved that antitank launchers (most notably, the old faithful RPG-7) still are quite effective against most modern armor, if used properly.
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