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AT4

From Wikipedia, the free encyclopedia
This article is about the unguided anti-tank weapon of Sweden. For the guided anti-tank missile of the Soviet Union/Russia, seeAT-4 Spigot.
"M136" redirects here. For other uses, seeM136 (disambiguation).

AT4
TypeDisposableanti-tanklauncher
Place of originSweden/United States
Service history
In service1987–present
Used bySeeOperators
WarsSeeWars
Production history
DesignerFörenade Fabriksverken
Manufacturer
Unit costUS$1,480[1]
No.built600,000+[2]
VariantsSeeVariants
Specifications
Mass6.7 kg (14.8lb) (AT4)[3]
8 kg (18 lb) (AT4-CS)
Length102 cm (40 in)[3]
Caliber84 mm
Muzzle velocity290 m/s (950 ft/s; 1,000 km/h), 220 m/s (720 ft/s; 790 km/h) (CS)[4]
Effective firing range300 m (point target)[3]
Maximum firing range500 m (area target)
2,100 m (maximum)
SightsIron sights,optionalAN/PVS-4night visionunit
FillingOctol
Filling weight440 ghigh-explosive anti-tank(HEAT) round
External images
Prototype AT4 Sweden tested 1981/82
image iconEarly AT4 with Swedish Soldier
image iconEarly AT4 launcher and projectile

TheAT4[a]is a Swedish 84 mm (3.31 in) unguided, man-portable, disposable,shoulder-firedrecoillessanti-tank weaponmanufactured bySaab Bofors Dynamics(formerly: FFV Ordance, later, Bofors Anti-Armour Systems).[5][unreliable source?]The AT4 is not arocket launcherstrictly speaking, because the explosive warhead is not propelled by arocket motor.Rather, it is a smooth-bore recoilless gun (as opposed to arecoilless rifle,which has arifledbarrel).[6]Saabhas had considerable sales success with the AT4, making it one of the most common light anti-tank weapons in the world.[7][8]TheM136 AT4is a variant used by theUnited States Army.

The name AT4 is a word play on the 84 mmcaliberof the weapon, (84) 'eighty four' being ahomophoneof 'A-T-4'.[9]The name also doubles as an Alpha -phonetic word play on the weapon's role, due to "AT" being a common military abbreviation for "anti-tank".[10]The name was created for export purposes as the nickname "eighty-four" was already a common English nickname for theCarl Gustaf 8.4 cm recoilless rifleafter its caliber.[9]

The AT4 is intended to giveinfantryunits a means to destroy or disablearmoured fighting vehiclesandfortifications,although it is generally ineffective against more modernmain battle tanks(MBTs), especially those withreactive armour,unless weaker sections of armour are exploited. The launcher and projectile are manufactured prepacked and issued as one unit of ammunition, with the launcher discarded after one use.

Development

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The AT4 is a development of the 74-mmPansarskott m/68[11](Miniman) adopted by theSwedish Armyin the late 1960s. Like the m/68, the AT4 was designed byFörenade Fabriksverken(FFV) and manufactured at their facility at Zakrisdal,Karlstad,Sweden.[5]FFV began research on a replacement for the m/68 in 1976, deliberately designing an individual anti-armour 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 armoured vehicles from any direction or MBTs from the sides or rear, and as an assault weapon effective against buildings and fortifications. FFV's prime design goal was a weapon that was simple to use, rugged, and far more accurate against moving targets than previous individual antiarmour weapons. Another key requirement was that the AT4 not only be able to penetrate armour, but also exhibit devastatingbeyond-armour effectafter 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.[12]

Even before the AT4 had been adopted by Sweden, it was entered into aUnited States Armycompetition for a new anti-tank weapon mandated by Congress in 1982 when theFGR-17 Viperfailed as a replacement for theM72 LAW.Six weapons were tested in 1983 by the US Army: the BritishLAW 80,the GermanArmbrust,the FrenchAPILAS,the Norwegian M72E4 (an upgraded M72 LAW), the US Viper (for baseline comparison purposes) and the Swedish AT4. The US 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,[13]with the Armbrust coming in second.[14]

Though very impressed with the simplicity and durability of the tested version of the AT4, the US 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 US Army as theLightweight Multipurpose WeaponM136.[15]The Swedish Army also recognized these improvements and subsequently adopted the Americanized version of the AT4 as thePansarskott 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 US Army version.

Due to the urban combat conditions that US military forces faced regularly during theIraq War,the US Army Close Combat Systems manager in charge of purchases of the AT4 suspended orders for the standard version of the AT4; US military forces instead only ordered the AT4 CS (Confined Space) version.[16]

Operation

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Seconds after firing an AT4 in combat in Iraq

The AT4 may be considered a disposable, low-cost alternative to aCarl Gustaf 8.4 cm recoilless rifle.The AT4 took many of its design features from the Carl Gustaf, which operates on the principle of arecoilless weapon,where the forwardinertiaof theprojectileis balanced by the inertia ofpropellantgases ejecting from the rear of the barrel. But unlike the Carl Gustaf, which uses a heavier and more expensive steel tube withrifling,[17]the disposable AT4 design greatly reduces manufacturing costs by using a reinforced smoothborefiberglassouter tube. Being a disposable gun also allows for lighter and cheaper construction. In a single-use disposable gun, the barrel only needs to be able to contain a single pressure spike when firing, when it can be disposed of, even if it is ruined, burnt-out and strained, unlike traditional guns which are required to survive many pressure spikes without failure and thus need to be strongly overbuilt and made of heat-proof materials. Pressures are also kept quite low compared to many traditional guns. This lightweight and thin barrel and low pressure, combined with the almost complete lack of recoil, means that relatively large projectiles (comparable to those found inmortarsandartillerysystems) can be utilised, which would otherwise be impossible in a man-portable weapon.

In the system originally developed by FFV for the Carl Gustaf, a plastic blowout plug is placed at the centre 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 adopted a unique method developed earlier by FFV: the spring-loaded firing rod is located down the side of the outer tube, with thefiring pinat the rear of the tube. When released, the firing pin strikes a primer located in the side of the casing's rim.

Firing the AT4-CS (2020)
Firing the M136 AT4 (2007)

The disadvantage of the recoilless design is that it creates a largeback blastarea behind the weapon, which can cause severe burns andoverpressureinjuries to friendly personnel in the vicinity of the user and sometimes even 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 was solved with theAT4-CS(Confined Space) version, specially designed forurban warfare.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. The AT4-CS version also reduced its muzzle velocity from the original 290 m/s to 220 m/s as part of its effort to be user-safe in a confined space, making the AT4-CS version more difficult to use as the drop is more pronounced. The effectiveness of the HEAT warhead is not dependent on speed.[citation needed]

To fire, the gunner first removes the safety pin located at the rear of the tube, which unblocks the firing rod. They then take a firing position, ensuring that no one is present in the back blast area. If firing from theprone position,they must also place their 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 hasiron sightsthat were originally developed for the cancelledViper,and are similar in concept and use to those on assault rifles.[18]They then remove the first of twosafetiesby 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 the firing button must be pressed down at the same time to fire the AT4. The red firing button has a similar resistance to the trigger pull of a rifle, so the gunner does not have to jab at the firing button, which could throw their aim off.

The AT4 is man-portable, as demonstrated by this French soldier carrying aFAMASrifle and an AT4.

After firing, the AT4 is discarded. Gunners are often trained to break off the sights after use, in order to prevent other soldiers from mistaking used launchers for unused ones. Unlike the heavier Carl Gustaf, the AT4 outer tube is built to take the stress of just one firing; it is not reusable and cannot be reloaded.

The AT4 can mount an opticalnight sighton a removable fixture. In US 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 that are identical in operation but fire reloadable9×19mmor20mmtracer ammunition.Both practice cartridges are unique to their respective weapons, with their trajectory matched to that of the live round. The 20mm version also has arecoilless weaponeffect with the same high noise and back blast as the AT4 firing and is favoured 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).

External images
AT4 version adopted by US as M136
image iconAT4 launcher shown with ammunition and HEAT projectile
image iconAT4 cutaway illustration showing ammunition installed
image iconAT4 front sight extended
image iconAT4 rear sight extended
image iconAT4 cock safety, press finger safety, and thumb firing button

Specifications

[edit]

Projectiles

[edit]

There are several different projectiles for the AT4. Because it is a one-shot weapon, projectiles are preloaded into the launcher tubes.[5]

AT4 launcher and projectile

High-explosive anti-tank(HEAT) – Can penetrate up to 45 centimetres (18 in) ofrolled homogeneous armour(RHA) withbeyond-armour effect.[19]

High-explosive dual purpose(HEDP) 502[5][20]– For use againstbunkers,buildings, enemy personnel in the open, and light armour. It can be set to detonate on impact or with a brief detonation delay. The heavier nose cap allows either to penetrate light walls or windows before exploding, or to be "skipped" off the ground for an air burst. For use against light armour, there is a smaller-cone HEAT warhead with 15 centimetres (5.9 in) penetration of RHA.

High penetration(HP) – Extra high penetration ability, up to 42–60 centimetres (17–24 in) of RHA.[21]

Anti-structure tandem-warheads(AST) – Designed for urban warfare where a projectile heavier than the HEDP AT4 is needed. This combines a shallow-coned HEAT warhead (resulting in low penetration but producing a wide hole) with atandem-chargeand a follow-through high-blast warhead. It has two settings: either to destroy bunkers or tomouse-holea building wall for combat entry.[22]

Complete AT4 HEAT antitank round (which is preloaded in AT4) and AT8 bunker-busting warhead
HEDP 502 projectile for the LMAW

Extended range(ER) – Anti-armor version with HEAT warhead. Range is extended from 300 to 600 metres (980 to 1,970 ft), with increased penetration up to 46 centimetres (18 in) of RHA. These major improvements add only about 2 kilograms of mass, despite being CS models.[23][21]

High explosive(HE) – High explosive anti-personnel weapon that can be set for impact orair-burstdetonation, with an effective range up to 1,000 metres (3,300 ft).[23]

Variants

[edit]

M136 AT4– American version with modified launch tube bumpers, sights, and slings.[24]

XM919 Individual Assault Weapon (also known as AT4CS TW) –American future variant, to enter service in 2025, and be delivered by 2029 for USD $500 million.[25]

Bunker-busting(AT8) – An AT4 version where the standard HEAT projectile is replaced with the bunker-busting warhead developed for theMk 153 Shoulder-Launched Multipurpose Assault Weapon(SMAW). No orders were ever placed.[26]

AT12-T– In the early 1990s, there were tests of atandem charge120 mm version (Bofors AT 12-T). The 14 kg weapon had a claimed penetration of 90 centimetres (35 in) RHA,[27]and in 1994 was demonstrated to defeat two NATO Single Heavy targets inclined at 68 degrees from vertical with ERA,[28]for a line-of-sight penetration of 600 mm. However, the project was cancelled due to the dissolution of theSoviet Unionand the subsequent cuts in Western defence budgets.[citation needed]

Operators

[edit]
AT4 84 mm
AT4 fired during Wessex Storm 2020

Wars

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See also

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References and notes

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Explanatory footnotes

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  1. ^Sometimes also spelled AT-4 or AT 4.

Citations

[edit]
  1. ^M136 AT4,FAS,archivedfrom the original on 3 April 2007,retrieved3 April2007
  2. ^abcKemp, Ian (April–May 2006), "The law gets tougher: the shoulder-launched light anti-armour weapon has evolved to become a multipurpose assault weapon much in demand for asymmetric warfare",Armada International,ISSN0252-9793
  3. ^abcMcManners, Hugh (2003).Ultimate Special Forces.DK Publishing.ISBN0-7894-9973-8.
  4. ^Owen, William F. (2007)."Light Anti-Armour Weapons: Anti-Everything?"(PDF).Asian Military Review.Archived fromthe original(PDF)on 7 July 2011.Retrieved12 May2010.
  5. ^abcdefghijklm"AT4 Light Anti-Armour Weapon".Army Technology. 30 April 2018.Archivedfrom the original on 7 May 2016.
  6. ^"84mm M136 (AT-4) Projected Grenade".Collective Awareness to UXO.Archived fromthe originalon 3 August 2022.Retrieved3 August2022.
  7. ^Atlamazoglou, Stavros (20 February 2024)."AT4: NATO Orders Proven Anti-Tank Weapon Used in Ukraine".The National Interest.Retrieved15 April2024.Made in Sweden by SAAB, the AT-4 is one of the most successful weapons in its category, with over a million sales.
  8. ^"France buys AT4 man-portable anti-tank weapon".mil.in.ua.28 January 2023.Retrieved15 April2024.Currently, the AT4 is one of the most popular and successful man-portable, disposable anti-tank weapon in the world.
  9. ^abÅkerström, Linda (2018).Den svenska vapenexporten.Sweden: Leopard Förlag. p. 72.ISBN9789173438384.
  10. ^Hewish, Mark, "FFV's Lightweight AT4, first of a new family of Swedish anti-armour weapons"International Defense Review,May 1980, p. 70.
  11. ^Pansarskottis a Swedish term that roughly translates to "armour shot".
  12. ^International Defense Review,May 1980, p. 71.
  13. ^The French APILAS was the only tested weapon that had the maximum penetration to defeat the frontal armour of the new Russian T-72 MBT, but it was rejected due to its weight and size.
  14. ^The Armbrust, while an impressive weapon with its almost total lack of launch signature, which enabled it to be fired from enclosed spaces, was rejected due to higher cost and lack of effective range against moving targets.
  15. ^The U.S. Army had so much grief in the early 1980s from various committee members of the U.S. Congress over the M72 LAW being officially referred to in manuals as a LightAntitankWeapon that they named the AT4 to make sure no member of Congress could question that again.
  16. ^John Antal. "Packing a Punch: America's Man-Portable Antitank Weapons". page 90.Military Technology.March 2010. ISSN 0722-3226.
  17. ^Until the 1980s the Carl Gustaf was constructed of high-alloy steel, but later versions used a thin steel liner containing the rifling, strengthened by acarbon fibreouter sleeve.
  18. ^FFV and the Swedish Army were so impressed by these sights that they adopted them for their AT4s; while adequate during the day, the original plastic sights were difficult to see at night or under low light conditions.
  19. ^"An Infantryman's Guide to Combat in Built-Up Areas"(PDF).bits.de.3 October 1995.Retrieved10 April2023.
  20. ^the complete disposable launcher and HEDP projectile is referred to by the manufacture in brochures as the LMAW (light multipurpose-assault weapon) see external links for link on early photos and press releases for further information on brochure
  21. ^ab"AT4 Family | Saab".
  22. ^"2008 SAAB video on AT4 versions including new multipurpose warhead for urban combat".YouTube.14 August 2008.Archivedfrom the original on 18 October 2014.Retrieved11 October2014.
  23. ^abSaab to integrate new projectile variants for disposable shoulder-launched rocket systemArchived24 December 2016 at theWayback Machine- Janes, 11 June 2014
  24. ^"AT4 Light Anti-Armour Weapon - Army Technology".Archivedfrom the original on 31 July 2018.
  25. ^"AT4CS TW wird die zukünftige Individual Assault Munition der U.S. Army"(in German). 28 August 2024.Retrieved29 August2024.
  26. ^Jane's Infantry Weapons 1995–96, page 220. The reference refers to Allaint Techsystems as the manufacture, but they soon after were acquired by Honeywell. TheSMAW-Doffered by Talley was chosen for the U.S. Army program that the AT4 entered. See external images at the SMAW-D link for an arms brochure on theFFV AT8
  27. ^"Small Arms Archive Detail Page for S00437".
  28. ^"Bofors demo 92 2-4".YouTube.13 December 2011.
  29. ^"Carl Gustaf, AT-4CS y fusiles Steyr HS.50 M1 para el Ejército Argentino".27 October 2017.Archivedfrom the original on 29 October 2017.Retrieved29 October2017.
  30. ^"La Infantería de Marina adquirió armamento antitanque descartable".Archived fromthe originalon 2 November 2010.Retrieved25 October2010.
  31. ^abcdeJones, Richard D (27 January 2009),Infantry Weapons 2009/2010(35 ed.), Jane's Information,ISBN978-0-7106-2869-5
  32. ^ab"The World Defence Almanac",World Defence Almanac: The Balance of Military Power,2000,ISSN0722-3226
  33. ^Replaced theAPILAS:AT 4 CS – L'arme anti blindé lourd AT 4 CS – The anti-heavy armor weapon,France: Ministry of Defense,archivedfrom the original on 8 January 2014,retrieved29 June2013
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