Rifle grenade

M7 grenade launcher with 22 mm grenade fitted on the end of an M1 Garand rifle.

A rifle grenade is a grenade that uses a rifle based launcher to permit a longer effective range than would be possible if the grenade was thrown by hand. The practice of projecting grenades with rifle-mounted launchers was first widely used during World War I and continues to the present, with the term 'rifle grenade' now encompassing many different types of payloads including high explosive, fragmentation, and anti-tank warheads as well as concussion, smoke, incendiary, and flare missiles. Many armies have replaced rifle grenades with dedicated grenade launchers.

Advantages and disadvantages

A grenade or shell fired from a rifle has these principle advantages compared to a hand-thrown grenade:

• Rifle grenade warheads can be projected from a rifle to a much greater distance than typical grenade launcher rounds.
• A rifle grenade can carry a larger, heavier payload a greater distance than a hand-thrown grenade.
• A rifle grenade is more accurate than a hand-thrown grenade, and is much more accurate when used against distant targets.
• A rifle grenade has the advantage of detonating upon impact, as compared to a hand-thrown grenade which commonly uses a timed detonation.

Offsetting these strengths are the heavier weight and bulk of rifle grenades compared to most hand grenades, combined with very high levels of recoil.

In comparison to a dedicated grenade launcher, the rifle grenade has four advantages:

• Rifle grenades can use a variety of different sizes and shapes of warheads and payloads.
• Rifle grenades can be projected from any infantry rifle fitted with an appropriate muzzle base or spigot tube fitting.
• Rifle grenades weigh less than an under barrel grenade launcher.
• Training rounds are re-usable.

The primary disadvantage of the rifle grenade is its relative inaccuracy compared to a dedicated low-velocity grenade launcher. Use of the rifle grenade also temporarily disables the normal use of the rifle in combat. This has increasingly led to the adoption of specialized low-velocity grenade launchers (using integrated shell/warheads) mounted to the rifle in a manner that does not obstruct immediate use of the rifle, such as underneath the rifle barrel. With the latter arrangement, the grenade launcher/rifle can be carried ready for immediate use. Low-velocity grenade launchers can also be fired from the shoulder without undue discomfort, something not normally possible with a rifle-launched grenade.

Operation

Japanese rifle grenade adapter

Rifle grenade with a stick

Historical rifle grenades used two different launching mechanisms:

• A stick that fits down the interior of the rifle barrel;
• A cup or special adapter that fitted on the end of the rifle muzzle.

For both these methods, a blank cartridge was required; in the former case, it propelled both the stick and the grenade. It was found that repeated use of a rifle for launching grenades by this method caused damage to the barrel, which is what led to the cup/adapter technique. The need to load a blank cartridge at the same time as the rifle grenade proved difficult in combat. Attempting to use a live round with either a stick or cup grenade launcher would have disastrous results.

The problem with having to load special ammunition has been addressed with the modern concepts of the "bullet trap" and "bullet through" rifle grenades. The SIMON breach grenade, for example, "traps" the live ball or tracer round within the grenade, and uses its energy for propulsion. "Bullet through" grenades, as for example the French Viven Bessieres (VB) used in World War I, have a hole through the middle that permits the passage of a standard bullet, and use the expanding gas to propel the grenade. Both of these methods remove the need for a special blank round to be loaded to launch.

Rifle grenades can be of any type as the more conventional hand grenades. However, two types predominate — fragmentation grenades, for use against personnel; and shaped charges for use against armoured fighting vehicles. Rifle grenades may be time-fused, so that they detonate at a fixed time after firing, or impact-fused, so they detonate upon impact. Generally, anti-personnel grenades are time-fused, and anti-armour grenades are impact-fused, though there are exceptions. A third type of rifle grenade is more rarely encountered, which uses a high explosive (HE) warhead. The high explosive warhead relies on blast effect rather than fragmentation to cause enemy casualties.

Often, special sights that attach onto the rifle to provide aiming for the grenade's particular ballistics are employed. Since rifle grenades usually travel at low velocities with very high trajectories, their range is measured in tens of yards (meters). The maximum range of most rifle grenades was about 200 yards (180 m). Rifle grenades are often fired at angles greater than 45 degrees, allowing them to drop down at steep angles to enter trenches, or to hit targets behind cover; the steep angle also increased the time of flight, to give the fuse more time to burn, so it would detonate as soon as possible after reaching the target. Firing at lower angles was useful for placing grenades through windows or other vertical openings.

History

German grenade rifles from the 16th century (wheellock) and 18th century (flintlock) in the Bayerisches Nationalmuseum, Munich

The grenade is an ancient weapon, and its revival and adaptation into the rifle grenade began around 1904. The first experiments are credited to a Japanese Colonel Amazawa, who experimented with rifle fired grenades during the Battle of Port Arthur in the Russo-Japanese War, and the idea was further used by the Spanish, though the French were the first to put it to widespread use during the trench warfare of World War I.^[1]

A French Mark I V-B rifle grenade and launcher

The French grenade, named the V-B grenade after its inventors, Vivien and Bessières, was fired from the standard service rifle with the use of a special adapter and a standard cartridge, providing an effective range of around 175 to 200 yards, while the effective radius of the bursting grenade was 75 yards. The grenade had a hollow through the middle, allowing the bullet to pass through, while the muzzle blast was captured by the launching device and used to propel the grenade. The bullet, after passing through the body of the grenade, struck a small plate that ignited primer. This then lit the fuse in the grenade, providing an eight second delay before detonation. It could be fired from the shoulder, but due to the heavy recoil and poor balance of the rifle fitted with the grenade, it was more common to fire it with the butt of the rifle resting on the ground, and either held at an appropriate angle, or resting on a tripod. The rifle grenade was useful in offense, particularly in attacking sandbag fortified machine gun nests, as well as in defense. Eight men armed with rifle grenades could fire 150 shots in a minute, providing a heavy barrage to break up an attacker's lines.^[2][3][4][5]

Upon entering the World War I, the United States attempted to adopt the V-B grenade, but this was not very successful. The difference between the French and American service cartridges (8 mm vs. 7.62 mm) meant that the grenade had to be re-designed with a smaller hole, but even this was not sufficient to ensure reliable functioning, due to differences in bullet design. The American bullet would often break apart in the grenade, and this led to the V-B derived grenade design being scrapped in May 1918.^[3]

Diagram of a Babbitt rifle grenade, used by the United States in World War I

The next United States attempt at a rifle grenade took a different track. The Babbitt grenade, developed by Colonel E. B. Babbitt of the U. S. Ordnance Department, used a long stem projecting from the rear of the grenade, which was slipped into the barrel of the Springfield 1903 rifle, and propelled with a special blank cartridge. The stem was calibrated with a number of grooves and a split ring, which allowed the user to set the grenade to slide a certain distance into the muzzle of the rifle. With the stem was inserted only part way, the chamber pressure upon firing was reduced, propelling the grenade a shorter distance. When fired at a 45 degree angle, ranges from 50 to 300 yards were possible; with the rifle angled at 80 degrees, ranges as short at 15 yards were possible. In addition to providing the force to propel the grenade, the gases from firing were directed through a hollow in the stem, and provided force to arm the grenade. Once armed, the grenade had a heavy plunger that would detonate the grenade upon impact.^[6][7]

After World War I, the rifle grenade was steadily modified to increase its effectiveness when launched from the rifle. The Japanese Army continued to experiment with rifle and hand-thrown grenades between the wars, and appear to be the first to have developed the rifle grenade as part of an entire weapons system. As part of this new concept, the Japanese Army adopted a new series of grenades, along with a new type of rifle grenade launcher. Rather than using the old cup-type launcher, like the French V-B grenade, the Japanese rifle grenade launcher was much smaller and lighter, and did not obstruct normal use of the rifle or its sights. Clamped to the muzzle of the rifle, a corresponding hollow-based, finned grenade fitted over the launcher tube, or spigot. The resulting assembly superficially resembled a spigot mortar, and became known in the West as a 'spigot' rifle grenade launcher. These spigot launchers still used special grenade-launching blank cartridges for firing.

Japanese Type 91 grenade, w/o tail assembly for spigot launcher

Prior to 1932, the Japanese Army had adopted a set of fragmentation grenades with almost universal adaptibility. Introduced in 1931, the Type 91 fragmentation grenade could be thrown by hand, discharged by a lightweight mortar-like projector (the Type 89, or knee mortar), or fitted with a stem and tail fins and fired from a spigot-type launcher as a rifle grenade.^[8] As the Type 91 grenade was fitted with a time fuse, it did not explode upon contact, and was designed to ignite its fuse while in flight when fired from the spigot launcher. Instead, a weak creep spring inside the grenade firing mechanism caused the firing pin to be thrown back upon launching, igniting the time fuse. Using this system, Japanese rifle grenades could be launched right through jungle cover or through small openings without the danger of premature detonation in the event the grenade struck an object on its way to the target.^[9]

The Italian Army adopted an unusual spigot-type 38.5 mm rifle grenade launcher bolted to the side of a normal Carcano 6.5 mm carbine, the Moschetto di Fanteria Mod. 91/28 con Tromboncino. In use, the rifle's bolt was removed and installed in the spigot launcher. The rifle was placed butt-first against the ground, a grenade blank and grenade were loaded, and the grenade was launched. The necessity of changing the rifle bolt kept the rifle out of use until the bolt could be replaced, a slow and clumsy procedure. The bolt-changing procedure could also result in lost rifle bolts in the heat of battle, putting the weapon out of action completely. As a result, this design was not adopted by any other nation. Today, it can be seen as an early, if unsuccessful ancestor of today's M203 under-barrel grenade launcher.

In the years just prior to World War II, more and more countries adopted spigot-type rifle grenade launchers and various finned rifle grenades, using anti-personnel (fragmentation) as well as anti-tank warheads. Another trend was seen in the development of 'bullet trap' rifle grenades, designed to dispense with the need to use blank rifle grenade ammunition. The bullet trap rifle grenade had a cavity through its center. Upon firing, the bullet passed through the grenade body, transferring its momentum to the grenade, which flew to its target and detonated in the usual manner.^[10]

Having come into wide acceptance during World War II, rifle grenades were increasingly used in the years after the war, including the wars in Korea, Algeria, and the early years of the Vietnam conflict. More and more countries adopted anti-tank rifle grenades with shaped-charge or HEAT warheads to enable infantrymen to defeat the thicker tank armour then coming into service. The Belgian ENERGA anti-tank rifle grenade design in particular was widely adopted by several Western nations. The 'bullet trap' rifle grenade design also saw increasing use during the years after World War II. Rifle grenade launchers were further simplified, and sometimes constructed as an integral part of the rifle itself. Eventually, most modern rifles began to use shortened spigot-base rifle grenade launchers incorporated into the rifle's own integral flash hider or muzzle compensator.

By the late 1970s, rifle grenades and their launchers began to be replaced by designated grenade launchers. First seen in the United States armed forces, these grenade launchers generally took form of either separate weapons (the M79 grenade launcher), or as an under-barrel attachment to an assault rifle (the most common example being the M203 attached to M16/M4-family of rifles).

Today, there is a return to the concept of the rifle grenade, such as the M16's SIMON breach grenade and the IMI Tavor's "Rephaim" advance grenade. Modern combination doctrine designates a certain percentage of grenadiers, or soldiers equipped with a grenade launcher or combination rifle/grenade launcher. The criticism of this doctrine is that if the grenadiers in a group are disabled or separated from the group, then the group has completely lost the grenade launcher as a heavy fire support. With rifle grenades, each soldier would be equipped with a small number of grenades, so every individual soldier could use some form of heavy firepower.

Less lethal use

A riot control grenade in a launching cup attached to a Mossberg 500 riot shotgun

The advent of less lethal grenades for riot control has led to the creation of gun launched versions of these grenades, though they are typically launched by riot shotguns, not rifles. These systems use a cup-type launcher attached to the muzzle of the gun to launch various less lethal grenade types.^[11]

Legal issues

In almost all countries, grenades are illegal for civilian ownership, though dummies (inert grenades with no fuse, detonator or explosives) are usually legal.

In the United States, rifle grenades containing explosive material are covered under the National Firearms Act as "destructive devices". Inert rifle grenades are not federally regulated, nor are rifle grenade launching attachments and devices. However, such items may be restricted by local legislation, as is the case in California.

See also

• Grenade launcher
• Portuguese Colonial Wars
• Type 89 grenade discharger

References

External links

• Type 90 Rifle Grenades
• http://www.firstworldwar.com/weaponry/graphics/serbiangrenade.jpg
• Carcano Model 91/28 with Tromboncino