AT4
Encyclopedia
The AT4 is an 84-mm unguided, portable, single-shot recoilless smoothbore weapon built in Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

 by Saab Bofors Dynamics
Saab Bofors Dynamics
Saab Bofors Dynamics, located in Karlskoga and Linköping, Sweden, is a subsidiary of Saab AB that specializes in military materiel such as missile systems and anti-tank systems....

 (previously Bofors Anti-Armour Systems). Saab
Saab
Saab AB is a Swedish aerospace and defence company, founded in 1937. From 1947 to 1990 it was the parent company of automobile manufacturer Saab Automobile, and between 1968 and 1995 the company was in a merger with commercial vehicle manufacturer Scania, known as Saab-Scania.-History:"Svenska...

 has had considerable sales success with the AT4, making it one of the most common light anti-tank
Anti-tank warfare
Anti-tank warfare was created by the need to seek technology and tactics to destroy tanks and their supporting infantry during the First World War...

 weapons in the world.

The designation "CS" represents "confined space" referring to the propellant charge being designed to operate effectively within buildings in an urban environment. It is intended to give infantry
Infantry
Infantrymen are soldiers who are specifically trained for the role of fighting on foot to engage the enemy face to face and have historically borne the brunt of the casualties of combat in wars. As the oldest branch of combat arms, they are the backbone of armies...

 units a means to destroy or disable armored vehicles and fortification
Fortification
Fortifications are military constructions and buildings designed for defence in warfare and military bases. Humans have constructed defensive works for many thousands of years, in a variety of increasingly complex designs...

s, although it is not generally sufficient to defeat a modern main battle tank
Main battle tank
A main battle tank , also known as a battle tank or universal tank, is a tank that fills the heavy direct fire role of many modern armies. They were originally conceived to replace the light, medium, heavy and super-heavy tanks. Development was spurred onwards in the Cold War with the development...

 (MBT). The launcher and projectile are manufactured prepacked and issued as a single unit of ammunition with the launcher discarded after a single use.

Development

The AT4 is a development of the 74-mm Pansarskott m/68
Miniman antitank weapon
The Miniman is a disposable single-shot 74-mm unguided anti-tank smooth bore recoilless weapon, designed in Sweden by Försvarets Fabriksverk and became operational in 1968. The Miniman is delivered with the HEAT projectile pre-loaded launch tube...

  (Miniman), adopted by the Swedish Army
Swedish Army
The Swedish Army is one of the oldest standing armies in the world and a branch of the Swedish Armed Forces; it is in charge of land operations. General Sverker Göranson is the Supreme Commander-in-Chief of the Army.- Organization :...

 in the late 1960s. Like the m/68, the AT4 was designed by Försvarets Fabriksverk (FFV) and manufactured at their facility at Zakrisdal, Karlstad
Karlstad
Karlstad is a city, the seat of Karlstad Municipality, the capital of Värmland County, and the largest city in the province Värmland in Sweden. The city had 61,685 inhabitants in 2010 out of a municipal total that during the first quarter 2010 was 84,885 inhabitants...

, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

. FFV began research in a replacement for the m/68 in 1976, deliberately designing an individual antiarmor weapon that would not be able to defeat the heavy armour protection of MBTs (main battle tanks) in frontal engagements, believing that to be counterproductive. The AT4 was designed as a weapon to engage medium to light armored vehicles from any direction, MBTs from the sides or rear, and as an assault weapon against buildings and fortifications. FFV also had the design goal of a weapon that was simple to use, rugged and was far more accurate than previous individual antiarmor weapons against moving targets. Another key requirement was that the AT4 not only be able to penetrate armor, but also have a devastating beyond-armour effect
Beyond-armour effect
Beyond-Armour Effect is a term coined by Försvarets Fabriksverk , a semi-governmental Swedish defense firm, while developing the AT4. From the 1980s this phrase was used in its brochures, press releases, weapon instruction manuals and other documentation to denote the post-penetration effect of...

 after penetration. FFV and the Swedish Army began the first evaluation firings of the prototype AT4s in the spring of 1981 with 100 tested by early 1982.

Even before the AT4 had been adopted by Sweden, it was entered into a U.S. Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 competition for a new anti-tank weapon mandated by Congress in 1982 when the FGR-17 Viper
FGR-17 Viper
The FGR-17 Viper was an USA one man disposable antitank rocket which had slated in the 1980s to be the replacement for the M72 LAW, but was canceled shortly after production began due a major public scandal resulting from massive cost overruns and safety concerns, as well as a mistaken belief by...

 failed as a replacement for the M72 LAW
M72 LAW
The M72 LAW is a portable one-shot 66 mm unguided anti-tank weapon, designed in the United States by Paul V. Choate, Charles B. Weeks, and Frank A. Spinale et al...

. Six weapons were tested in 1983 by the US Army: the British LAW 80
LAW 80
The LAW 80 , sometimes erroneously referred to as LAW 94, is a man-portable, disposable anti-tank weapon currently in use by the British Army and a few other militaries.-Description:...

, the German Armbrust
Armbrust
Armbrust is a lightweight unguided anti-tank weapon designed and developed by Messerschmitt-Bölkow-Blohm of Germany, who later sold its manufacturing rights to Chartered Industries of Singapore ....

, the French APILAS
APILAS
APILAS is a portable one-shot 112 mm recoilless anti-tank weapon, designed in France by GIAT Industries...

, the Norwegian M72E4 (an upgraded M72 LAW), the U.S. Viper (for baseline comparison purposes) and the Swedish AT4. The U.S. Army reported to Congress in November 1983 that the FFV AT4 came the closest to meeting all the major requirements established to replace the M72 LAW, with the Armbrust coming in second.

Though very impressed with the simplicity and durability of the tested version of the AT4, the U.S. Army saw some room for improvement, specifically the addition of rear and front bumpers on the launch tube and changes to the sights and slings. After these changes, the AT4 was adopted by the U.S. Army as the Lightweight Multipurpose Weapon M136. The Swedish army also recognized these improvements and subsequently adopted the Americanized version of the AT4 as the Pansarskott m/86 (Pskott m/86), with the addition of a forward folding hand grip to help steady the AT4 when being aimed and fired. The forward folding grip is the only difference between the AT4 adopted by Sweden and the U.S. Army version.

Due to the urban combat conditions that US military forces in the last several years have been facing regularly, the US Army Close Combat Systems manager in charge of purchases of the AT4, suspended orders for the standard version of the AT4, and are now ordering only the AT4 CS version.

Operation

The AT4 may be compared to a less-expensive one-shot Carl Gustav recoilless rifle
Carl Gustav recoilless rifle
The Carl Gustav is the common name for the 84 mm man-portable reusable multi-role recoilless rifle produced by Saab Bofors Dynamics in Sweden...

. The AT4 took many of its design features from the Carl Gustav, which operates on the principle of a recoilless weapon, where the forward inertia
Inertia
Inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion. It is proportional to an object's mass. The principle of inertia is one of the fundamental principles of classical physics which are used to...

 of the projectile
Projectile
A projectile is any object projected into space by the exertion of a force. Although a thrown baseball is technically a projectile too, the term more commonly refers to a weapon....

 is balanced by the mass of propellant
Propellant
A propellant is a material that produces pressurized gas that:* can be directed through a nozzle, thereby producing thrust ;...

 gases ejecting from the rear of the barrel. But unlike the Carl Gustav, which uses a heavier and more expensive steel tube with rifling
Rifling
Rifling is the process of making helical grooves in the barrel of a gun or firearm, which imparts a spin to a projectile around its long axis...

, the disposable AT4 design greatly reduces manufacturing costs by using a reinforced smoothbore fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...

 outer tube. Since recoilless weapons generate almost no recoil
Recoil
Recoil is the backward momentum of a gun when it is discharged. In technical terms, the recoil caused by the gun exactly balances the forward momentum of the projectile and exhaust gasses, according to Newton's third law...

, a relatively large projectile can be fired which would otherwise be impossible in a man-portable weapon.

In the system originally developed by FFV for the Carl Gustav, a plastic blowout plug is placed at the center rear of the shell casing containing the projectile and propellant, which itself is enclosed in the AT4 outer tube. When the gases build up to the correct pressure level, the blowout plug disintegrates allowing the proper amount of gases to be vented to the rear, balancing the propellant gases pushing the projectile forward.

The AT4 uses a unique method developed earlier by FFV and adopted for the AT4: the spring-loaded firing rod is located down the side of the outer tube, with the firing pin
Firing pin
A firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...

 at the rear side of the tube. When released, the firing pin strikes a primer located in the side of the casing's rim. Additionally, as the shell casing absorbs the majority of the firing stresses, the launch tube can be designed to be very lightweight as it does not have to contend with the extreme pressures found in traditional cannons.
The disadvantage of the recoilless design is that it creates a large back blast area behind the weapon which can cause severe burns and overpressure
Overpressure
The term Overpressure is applied to a pressure difference, relative to a "normal" or "ambient" pressure, in various circumstances:* In engineering: the pressure difference over the wall thickness of a pressure vessel...

 injuries both to friendly personnel in the vicinity of the user and sometimes to the users themselves, especially in confined spaces. The back blast may also reveal the user's position to the enemy.

The problem of back blast has been recently solved with the AT4-CS (Confined Space) version, specially designed for urban warfare
Urban warfare
Urban warfare is combat conducted in urban areas such as towns and cities. Urban combat is very different from combat in the open at both the operational and tactical level...

. This version uses a saltwater countermass in the rear of the launcher to absorb the back blast; the resulting spray captures and dramatically slows down the pressure wave, allowing troops to fire from enclosed areas.

To fire, the gunner first removes the safety pin located at the rear of the tube, which unblocks the firing rod. He then takes a firing position ensuring that no one is present in the back blast area. If firing from the prone position (lying on his stomach) he must also place his legs well to the side to avoid burning himself. Then the gunner moves back the front and rear sight covers, allowing the sights to pop up into their firing positions. The AT4 sights are iron sight
Iron sight
Iron sights are a system of shaped alignment markers used as a sighting device to assist in the aiming of a device such as a firearm, crossbow, or telescope, and exclude the use of optics as in telescopic sights or reflector sights...

s and were originally developed for the cancelled Viper, and are similar in concept and use to those on assault rifles. He then removes the first of two safeties by moving the firing rod cocking lever (located on the left side) forward and then over the top to the right side. The gunner takes aim, while at the same time holding down the red safety lever located in front of the cocking lever, and then fires by pressing forward the red firing button with his right thumb. Both the red safety lever and firing button must be pressed down at the same time to fire the AT4. The red firing button has resistance similar to the trigger pull of an assault rifle, so the gunner does not have to jab at the firing button which could throw his aim off.
After firing, the AT4 is discarded. Unlike the heavier Carl Gustav, the AT4 outer tube is built only to take the stress of one firing; it is not reusable and cannot be reloaded like the Carl Gustav.

The AT4 can mount an optical night sight on a removable fixture. In U.S. military use, the launcher can be fitted with the AN/PAQ-4C, AN/PEQ-2, or the AN/PAS-13 night sights.

The AT4 requires little training and is quite simple to use, making it suitable for general issue. However, as the cost of each launcher makes regular live-fire training very expensive, practice versions exist which are identical in operation but fire reloadable 9mm or 20mm
20 mm caliber
The 20 mm caliber is a specific size of cannon or autocannon ammunition, commonly the smallest caliber which is unambiguously a cannon and not a heavy machine gun....

 tracer ammunition
Tracer ammunition
Tracer ammunition are bullets that are built with a small pyrotechnic charge in their base. Ignited by the burning powder, the phosphorus tail burns very brightly, making the projectile visible to the naked eye...

. Both practice cartridges are unique to their respective weapons, with their trajectory matched to that of the live round. The 20mm version also has a recoilless weapon effect with same high noise and back blast as the AT4 firing and is favored by the Swedish army because of the added realism of the back blast as compared to the "plonk" sound of the 9mm round (similar to the sound of a finger tapping on an empty can).

Specifications

  • Length: 101.6 cm (40 in.)
  • Weight: 6.7 kg (14.77 pounds)
  • Bore diameter: 84 mm
  • Maximum effective range: 300 metres (328 yards), although it has been used in excess of 500 meters (547 yards) for area fire.
  • Penetration: 400 mm (15.7 inches) of rolled homogeneous armour
    Rolled homogeneous armour
    Rolled homogeneous armour is a type of steel which is used to armour vehicles.-Composition:Armoured steel must be hard yet impervious to shock in order to resist high velocity metal projectiles. Steel with these characteristics is produced by processing cast steel billets of appropriate size and...

     (RHA) (also see below)
  • Time of flight (to 250 metres, or 273 yards): less than 1 second
  • Muzzle velocity: 285 metres (950 ft) per second
  • Operating temperature
    Operating temperature
    An operating temperature is the temperature at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the...

    : -40 to +60°C (-40 to +140°F)
  • Ammunition: Fin-stabilized projectile with HEAT
    Heat
    In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

     warhead

Projectiles

There are several different projectiles for the AT4. Note that since the AT4 is a one-shot weapon, these projectiles are preloaded into the launcher tubes.
HEDP 502 (High Explosive Dual Purpose)
For use against bunker
Bunker
A military bunker is a hardened shelter, often buried partly or fully underground, designed to protect the inhabitants from falling bombs or other attacks...

s, buildings, enemy personnel in the open and light armor. The projectile can be set to detonate on impact or with a slight delayed detonation. The heavier nose cap allows the HEDP projectile to penetrate light walls or windows and then explode, or "skipped" off the ground for an air-burst. For use against light armor, there is a smaller cone HEAT warhead with 150 mm (5.9 inches) of penetration against RHA.


HP (High Penetration)
Extra high penetration ability (up to 500 mm (19.7 inches) to 600 mm (23.6 inches) of RHA.)


AST (Anti Structure Tandem-warheads)
Designed for urban warfare where a projectile heavier than the HEDP AT4 is needed. Two warheads, first one a HEAT with a shallow cone resulting in less penetration but a wider hole, and a second follow through high-blast warhead. It has two settings: one for destroying bunkers and one for mouse holing a building wall for combat entry.

HEAT (High Explosive Anti-Tank)
The AT4 HEAT can penetrate up to 420 mm (16.5 inches) of RHA
Rolled homogeneous armour
Rolled homogeneous armour is a type of steel which is used to armour vehicles.-Composition:Armoured steel must be hard yet impervious to shock in order to resist high velocity metal projectiles. Steel with these characteristics is produced by processing cast steel billets of appropriate size and...

 with beyond-armour effect
Beyond-armour effect
Beyond-Armour Effect is a term coined by Försvarets Fabriksverk , a semi-governmental Swedish defense firm, while developing the AT4. From the 1980s this phrase was used in its brochures, press releases, weapon instruction manuals and other documentation to denote the post-penetration effect of...

.


AT8 (Bunker Busting)
A version of the AT4 where the standard HEAT projectile is replaced with the bunker busting warhead developed for the SMAW
Shoulder-Launched Multipurpose Assault Weapon
The Shoulder-Launched Multipurpose Assault Weapon is a shoulder-launched rocket weapon, based on the Israeli B-300, with the primary function of being a portable assault weapon and a secondary anti-armor rocket launcher. It was introduced to the United States armed forces in 1984...

. No orders placed.


AT12 (130mm Frontal Engagement Version)
In the early 1990s, there were tests of a tandem charge 130-mm version (Bofors AT 12) that would be able to penetrate the front armor of any modern main battle tank. However, the project was canceled due to the dissolution of the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 and cuts in Western defense budgets.

Users

Argentine Marines.: Designated PVV M/95 (Panserværnsvåben Model 1995).: Designated ABL (Anti Blindé Léger) by the French Army
French Army
The French Army, officially the Armée de Terre , is the land-based and largest component of the French Armed Forces.As of 2010, the army employs 123,100 regulars, 18,350 part-time reservists and 7,700 Legionnaires. All soldiers are professionals, following the suspension of conscription, voted in...

.: American forces supplied the Iraqi military with AT4 weapons.: Called the SRAAW (Short Range Anti Armour Weapon) by the Irish Defence Forces.: Roughly 1,000 pieces purchased.: Lithuanian Armed Forces. (Replaced by Pzf-3
Panzerfaust 3
The Panzerfaust 3 is a modern and disposable recoilless RPG anti-tank weapon developed between 1978 and 1985 and put into service by the Bundeswehr in 1992...

): Designated Pansarskott m86.: Small quantities of AT4 and HP projectiles purchased.: Designated M136 AT4 in USMC
United States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...

 and United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

 service, beginning in early 1987. The AT4 was used in the U.S. invasion of Panama
United States invasion of Panama
The United States Invasion of Panama, code-named Operation Just Cause, was the invasion of Panama by the United States in December 1989. It occurred during the administration of U.S. President George H. W...

, the Afghanistan War, the Gulf War
Gulf War
The Persian Gulf War , commonly referred to as simply the Gulf War, was a war waged by a U.N.-authorized coalition force from 34 nations led by the United States, against Iraq in response to Iraq's invasion and annexation of Kuwait.The war is also known under other names, such as the First Gulf...

, and the Iraq War. Over 300,000 have been built locally, under license by ATK
Alliant Techsystems
Alliant Techsystems Inc., most commonly known by its ticker symbol, ', is one of the largest aerospace and defense companies in the United States with more than 18,000 employees in 22 states, Puerto Rico and internationally, and 2010 revenues in excess of an estimated...

.: The AT4 has been in the Venezuelan arsenal since the 1980s. In 2009, it was reported that AT4 weapons sold to Venezuela had been captured from FARC insurgents in Colombia, leading Colombia to accuse Venezuela of selling the weapons to the insurgents, and heightening tensions between the two countries.

External links

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