M67 Grenade

A Frag Grenade (hand grenade) is a small hand-held anti-personnel weapon designed to be thrown, which then explodes after a short time. The word "grenade" is derived from the Old French (pome) grenate ("pomegranate"), in reference to the general size of early grenades, and because its shrapnel pellets reminded soldiers of the seeds of this fruit. Grenadiers were originally soldiers who specialized in throwing grenades.

Not all grenades are thrown by hand. Several types are fired from rifles or purpose-designed grenade launchers. For example, tear gas grenades used in riot control are fired from riot guns, and the M203 is a grenade launcher that can be fitted to several types of rifles such as the M4 carbine.

Characteristics
Hand grenades share the following four characteristics:
 * Their employment range is short;
 * Their effective casualty radius is small;
 * Their delay element permits safe throwing;
 * Their hard shell, along with their previously mentioned delay element, enables the grenade to ricochet off hard surfaces, like walls, before detonating.

Hand grenades have the following main parts:
 * The body contains the filler and, in some grenades, also provides the fragmentation;
 * The filler is the chemical or explosive substance in the grenade, which determines the grenade's use and characteristics;
 * The fuse assembly causes the grenade to function by igniting or detonating the filler.



Using grenades
A classic hand grenade has a safety handle or lever (sometimes called by the slang term, "spoon") and a removable safety pin that prevents the handle from being released. In transit, some grenade types also have a safety clip to further prevent the handle from coming off.

To use a grenade the soldier grips it firmly with his/her throwing hand, ensuring that the safety lever is firmly held in place with the thumb, left-handed soldiers are advised to actually invert the grenade - ensuring that the thumb is still the digit holding the safety lever in place. The pull ring of the safety pin is then grasped with the index or middle finger of the non-throwing hand and the safety pin is removed using a pulling and twisting motion. The grenade is then thrown towards the target, an over-arm throw is recommended but may not be suitable for an actual combat situation. Soldiers are trained to throw grenades in standing, prone-to-standing, kneeling, prone-to-kneeling, and alternate prone positions and in under- or side-arm throws. If the grenade is thrown from a standing position the thrower must then immediately seek cover or lie prone if no cover is nearby.

Once the grenade is thrown the safety lever is released and the striker throws the safety lever away from the grenade body as it rotates to detonate the primer. The primer explodes and ignites the fuse (sometimes called the delay element), the fuse burns down and activates the detonator which explodes the main charge.

When using an antipersonnel grenade, the objective is to have the grenade explode so that the target is within its effective radius. For the M67 fragmentation grenade used by several NATO nations, the effective kill zone has a five meter radius, while the casualty-inducing radius is approximately fifteen meters. Fragments can fly as far as 230 meters.

"Cooking off" is a term referring to intentionally holding onto an armed grenade after the pin has been pulled and the handle released, to decrease the amount of time to detonation after throwing. This technique is used to reduce the ability of the enemy to take cover or throw the grenade back. It is also used to allow the grenade to burst in the air over defensive positions. This technique is inherently dangerous, since fuses may vary from grenade to grenade. Because of this the U.S. Marines (MCWP 3-35) describe cooking-off as the "least preferred technique", recommending a "hard throw, skip/bounce technique" to prevent an enemy returning a grenade.

A call is usually given upon deploying a grenade, to warn friendly forces. Some yells, such as "grenade" or "fire in the hole" are used when a grenade has been thrown in by an enemy; in any instance the purpose is to give notice to fellow soldiers to take cover.

In the U.S. Military, when a grenade is dropped into an enclosed space like a tunnel, room, or trench, the person dropping the grenade should yell "fire in the hole" to warn that an explosion is about to occur. Other U.S. military procedures include calling "frag out" to indicate that a fragmentation grenade has been deployed.

Grenades are often used in the field to construct booby traps, using some action of the intended target (such as opening a door, or starting a car) to trigger the grenade. These grenade-based booby traps are simple to construct in the field using readily available materials. The most basic technique involves wedging a grenade in a tight spot so the safety lever does not leave the grenade when the pin is pulled. A string is then tied from the head assembly to another stationary object. When a soldier steps on the string, the grenade is pulled out of the narrow passageway, the safety lever is released, and the grenade detonates.

Abandoned booby traps and discarded grenades contribute to the problem of unexploded ordnance. The use of trip wire-triggered grenades (along with land mines in general) is banned under the Ottawa Treaty and may be treated as a war crime wherever it is ratified.



The People's Republic of China, the United States, and Russia have not signed the treaty despite international pressure, citing self-defense needs. The United States is, however, a signatory of the 1996 Protocol on Prohibitions or Restrictions on the Use of Mines, Booby-Traps and Other Devices. The 1996 Protocol restricts use of mines to regions and situations where the mined areas are known, clearly marked, and access is controlled so as to minimize civilian casualties. In signing the 1996 Protocol, the United States made a reservation that 'mines' as defined in the treaty would not apply to booby trap-rigged hand grenades.



Classical "pineapple" grenades, such as the Mills bomb, used smokeless powder and cast-iron shells, which (in theory) fragmented along deliberately-cast weak points in the shell, although the pattern on the grenade body was actually intended to allow the user to keep a firm grip on the grenade. In practice, external grooves in the grenade body turned out to have little or no effect on the size and shape of fragments formed.

Grenades have also been made to release smoke, tear gas and other gases, as well as illumination. Special forces often use stun grenades to disorient people during an entry into a room.

Some grenade designs were made to be thrown longer distances. The German "potato-masher" grenade had a long wooden handle that extended its range by fifty percent. The "potato-masher" was fired by a friction igniter in the head, which was activated by a pull string threaded through the hollow handle. Immediately before throwing the grenade, the soldier pulled a small plastic ring attached to a string attached to the friction igniter. This started the time fuse which fired the detonator after a delay. The "potato-masher" is often incorrectly thought to have had an impact fuse. It did not, but the superficially similar British stick grenade design of 1908 did.

Fragmentation grenades
The fragmentation grenade (commonly known as a "frag") is an anti-personnel weapon that is designed to disperse shrapnel upon exploding. The body is made of hard plastic or steel. Flechettes, notched wire, ball bearings or the case itself provide the fragments. When the word "grenade" is used without qualification, and context does not suggest otherwise, it is generally assumed to refer to a fragmentation grenade.

These grenades were sometimes classed as defensive grenades because the effective casualty radius of some matched or exceeded the distance they could be thrown, thus necessitating them being thrown from behind cover. The Mills bomb or F1 grenade are examples of defensive grenades where the 30–45 m casualty radius matched or exceeded the 30 m that a grenade could reasonably be thrown.

Modern fragmentation grenades such as the United States M67 grenade have a wounding radius of 15 m (half that of older style grenades which may still be encountered) and can be thrown about 40 m. Fragments may travel more than 200 m.

Concussion grenades
The concussion grenade is an anti-personnel device that is designed to damage its target with explosive power alone. Compared to fragmentation grenades, the explosive filler is usually of a greater weight and volume. The case is far thinner and is designed to fragment as little as possible. The overpressure produced by this grenade when used in enclosed areas is greater than that produced by the fragmentation grenade. Therefore, it is especially effective in enclosed areas.

These grenades are usually classed as offensive weapons because the effective casualty radius is smaller than the distance it can be thrown.

The US MK3A2 concussion grenade is filled with TNT and has a body made of tarred cardboard.

The term 'concussion' is often erroneously applied to stun grenades. This is not descriptive of the effects caused by the grenade. The term 'concussion' is used because the grenade relies on its explosive power to create casualties.

Percussion grenades


A percussion grenade detonates upon impact with the target. Classic examples of percussion grenades are the British Gammon bomb and No. 69 grenade. Timed fuse grenades are generally preferred to hand-thrown percussion grenades because their fuzing mechanisms are safer and more robust than those used in percussion grenades. Some percussion grenades have a conventional pyrotechnic fuse fitted as a backup detonation device.

Smoke grenades


Smoke grenades are used as ground-to-ground or ground-to-air signaling devices, target or landing zone marking devices, and screening devices for unit movement. The body is a sheet-steel cylinder with emission holes in the top and bottom. These allow the smoke to be released when the grenade is ignited. Two main types exist, colored smoke (for signaling) and screening smoke. In colored smoke grenades, the filler consists of 250 to 350 grams of colored smoke mixture (mostly potassium chlorate, lactose and a dye). Screening smoke grenades usually contains HC (hexachloroethane/zinc) smoke mixture or TA (terephthalic acid) smoke mixture. HC smoke is harmful to breathe, since it contains hydrochloric acid. Whilst not intended as a primary effect, these grenades can generate enough heat to scald or burn unprotected skin and the spent casing should not be touched until it has cooled.

Riot control


Contrary to popular belief, gas-expelling grenades are rarely used to disperse large groups, because of the risk of causing generalized panic. Grenades are instead used to create barriers of tear gas in order to direct the movement of large groups of people, or to protect police officers on the verge of being overwhelmed. As an exception, tear gas may be used to disperse a mob surrounding a small centralized group.

Similarly, gas-expelling grenades are not often used to force criminals out of cover because of the risk of intoxicating people in enclosed areas, although SWAT teams will occasionally employ CS gas grenades to facilitate the arrest of an armed suspect, especially if there are no bystanders in the area. This kind of deployment is most often used in an area where several suspects have a large amount of cover, since the functioning of other distraction grenades will be hindered.

Tear gas grenades are similar to smoke grenades in terms of shape and operation. In tear gas grenades the filler is generally 80 to 120 grams of CS gas combined with a pyrotechnic composition which burns to generate an aerosol of CS-laden smoke. This causes extreme irritation to the eyes and, if inhaled, to the nose and throat. (See also the Branch Davidian siege). Occasionally CR gas is used instead of CS.

Incendiary grenades


Incendiary grenades produce intense heat by means of a chemical reaction. The body is practically the same as that of a smoke grenade. The filler is 600 to 800 grams of thermate, which is an improved version of World War II-era thermite. The chemical reaction that produces the heat is called a "thermite reaction". In this reaction, aluminium metal and iron oxide react to produce iron and aluminium oxide. This reaction produces a tremendous amount of heat, burning at 2200 °C (4000 °F). This makes incendiary grenades useful for destroying weapons caches, artillery, and vehicles. Other advantages include its ability to function without an external oxygen source, allowing it to burn underwater.

White phosphorus (also used in smoke grenades; see above) can also be used as an incendiary agent. It burns at a temperature of 2800 °C (5000 °F).

Thermite and white phosphorus cause some of the worst and most painful burn injuries because they burn so quickly and at such a high temperature. In addition, white phosphorus is very poisonous: a dose of 50-100 milligrams is lethal to the average human.

A common improvised incendiary grenade is the Molotov Cocktail.

Stun grenades


Stun grenades, also called NFDDs (Noise and Flash Diversionary Devices), "flash & bang" grenades, or flashbangs, were originally designed for the British Special Air Service as an incapacitant. Stun grenades are used to confuse, disorient, or distract a potential threat. A stun grenade can seriously degrade the combat effectiveness of affected personnel for up to a minute. The best known example is the M84 Stun Grenade, which produces a blinding (6-8 million Candela) flash and deafening (170-180 dB SPL) blast. This grenade can be used to incapacitate people, generally without causing serious injury. Standing operating procedure for LAPD SWAT has officers deploy flashbangs close to the point of entry. This is because all attention will be directed towards the door once it has been breached, and deploying the flashbang close to this point heightens the chances that a suspect will be affected by the device.

The flash of light momentarily activates all photosensitive cells in the retina, making vision impossible for approximately five seconds until the eye restores the retina to its original, unstimulated state. Subjects affected by flashbangs describe seeing a single frame for the five seconds (as if their vision was "paused") until it fades and normal sight returns. This is because the sensory cells which have been activated continue sending the same information to the brain until they are restored to their resting state, and the brain translates this continuous information into the same image. The incredibly loud blast emitted by the grenade contributes to its incapacitative properties by disturbing the fluid in the semicircular canals of the ear. The semicircular canals consist of three half circles of tubing, each oriented in one of the three planes of motion, that are filled with fluid. The walls of the tubes are lined with hair cells which use their small, hairlike cilia to detect the motion of the fluid. This establishes a person's sense of balance and movement through space. When a stun grenade detonates, the fluid in the semicircular canals is disturbed, and with it the subject's sense of balance.

Upon detonation, the fuse/grenade body assembly remains intact and produces no fragmentation. The body is a steel hexagonal tube with holes along the sides which allow a blast of light and sound to be emitted. This is done to prevent injury from shrapnel but you can also receive a burn as it is still a explosion as the swat teams have had a few fires from the grenade landing on a chair or long haired carpet. However, injuries resulting from the concussive properties of the detonation sometimes occur. The filler consists of about 4.5 grams of a pyrotechnic metal-oxidant mix of magnesium and ammonium perchlorate or potassium perchlorate.

Sting grenades
Sting grenades are based on the design of the fragmentation grenade. Instead of using a metal casing to produce shrapnel, they are made using two spheres of hard rubber. Inside the smaller sphere is the explosive charge, primer, and detonator. The space between the two spheres is then filled with many small, hard rubber balls. Upon detonation, the subject is incapacitated by the blunt force of the projectiles. The advantage to using sting grenades comes from the fact that the subject is very often incapacitated, winded, or at the very least dislodged from cover.

Some types have an additional payload of chemical agents like CS gas.

The advantages compared to a flashbang are
 * The "plug 'n shut" tactic, which is shutting one's eyes and plugging one's ears to avoid being affected by a flashbang. This does nothing to protect a person from a sting grenade.
 * The subject does not need to be looking at the grenade for it to take its full effect.
 * Sting grenades are much more likely to cause a subject to either fall or lower himself in pain, thus providing good sight lines to unaffected targets in the area.

This makes sting grenades ideal for containing small groups of rowdy prisoners, providing a shooting opportunity when a suspect is hiding behind cover, or in allowing SWAT teams to clear small rooms.

A disadvantage of using sting grenades is that they are not sure to incapacitate a subject, so it is dangerous to use if the subject is armed. This arises from the fact that sting grenades rely on the body's reaction to adverse stimuli (pain and blunt force trauma) rather than denial of sensory input. A person with sufficient mental focus can concentrate enough to ignore being hit by a sting grenade's payload, whereas a stun grenade will physically affect vision and sense of orientation. The effective range of a sting grenade is limited compared to a stun grenade.

Impact stun grenades - Blank Firing Impact Grenade or BFIG
A more recent development is the Blank Firing Grenade (BFIG or Blank Firing Impact Grenade). Preferred in many situations, especially training, for two main reasons; they are re-usable - and therefore more economical - because the charge is a standard ammunition blank, and they are subject to very few transport restrictions when unloaded. The BFIG contains a mechanism to fire a blank cartridge when dropped at any angle onto a hard surface from a height of a metre or more. Firing will occur in any combination of positions only on impact. 

Anti-tank grenades
The first anti-tank grenades were improvised devices usually made by putting a number of fragmentation grenades into a sandbag or by tying them together. Due to their weight, these were normally thrown from very close range or directly placed in vulnerable spots onto an enemy vehicle.

Purpose-designed anti-tank grenades invariably use the shaped charge principle to penetrate the tank's armor. This means that the grenade has to hit the vehicle at an exact right angle for the effect to work properly. This is achieved by the grenade deploying a small drogue parachute or fabric streamers after being thrown.

Britain put the first anti-tank grenade into the field during the Second World War with the rifle-fired No 68 AT Grenade. Also developed by the UK during the Second World War, was the No 74 ST Grenade popularly known as a sticky bomb; the main charge was held in a sphere covered in adhesive. In anticipation of a German invasion, it was produced in substantial numbers. Inherently dangerous for the user, it was relegated to Home Guard use.

During World War II, when tanks overran entrenchments, anti-tank mines could be and were used by infantry as an improvised hand grenades by placing or throwing them in the path of a tank in the hope of disabling a track.

The most widely-distributed anti-tank grenades are the Russian designs of the 1950s and later, mainly the RKG-3.

Due to improvements in modern tank armor, anti-tank hand grenades are generally considered obsolete. However in recent conflict, namely the Iraq War, the RKG-3 anti-tank hand grenade has made a reappearance in the service of insurgents who utilize them primarily against US Humvees, which lack the heavier armor of tanks.