M113 armored personnel carrier

Development

The M113 was developed by Food Machinery Corp. (FMC), which had produced the earlier M59 and M75 Armored personnel carriers. The M113 bears a very strong resemblance to both of these earlier vehicles. The M75 was too heavy and expensive to be useful; its weight prevented amphibious capability, and being transported by air. The lightened M59 addressed both of these problems, but ended up with too little armor, and was unreliable as a result of efforts to reduce its cost.

The army was looking for a vehicle that combined the best features of both designs, the "airborne armored multi-purpose vehicle family" (AAM-PVF). of all-purpose, all-terrain armored fighting vehicles FMC had been working with Kaiser Aluminum and Chemical Co. in the late 1950s to develop suitable aluminum armor. It was known that use of this armor could produce a vehicle that provided the protection of the M75, and the light weight and mobility of the M59.

Food Machinery Corp. responded with two proposals; two versions of the aluminum T113—a thicker and a thinner armored one—along with the similar but mostly steel T117. The thicker-armored version of the T113, effectively the prototype of the M113, was chosen because it weighed less than its steel competitor, while offering the same level of protection. An improved T113 design, the T113E1, was adopted by the U.S. Army in 1960 as the "M113". A diesel prototype, T113E2, was put into production in 1964 as the "M113A1", and quickly supplanted the gasoline-engined M113. In 1994, FMC transferred the M113's production over to its newly formed defense subsidiary, United Defense. Then in 2005, United Defense was acquired by BAE Systems.

The M113 was developed to provide a survivable and reliable light tracked vehicle able to be air-lifted and air-dropped, by C-130 and C-141 transport planes. The original concept was that the vehicle would be used solely for transportation, bringing the troops forward under armor and then having them dismount for combat; the M113 would then retreat to the rear. Entering service with the U.S. Army in 1960, the M113 required only two crewmen, a driver and a commander, and carried 11 passengers inside the vehicle. Its main armament was a single .50-caliber (12.7 mm) M2 Browning machine gun operated by the commander.

On 30 March 1962, the first batch of 32 M113s arrived in Vietnam, and were sent to two Army of the Republic of Vietnam (ARVN) mechanized rifle companies, each equipped with 15 of the APCs. On 11 June 1962, the two mechanized units were fielded for the first time. During the Battle of Ap Bac in January 1963, at least fourteen of the exposed .50 caliber gunners aboard the M113s were killed in action, necessitating modifications to improve crew survivability. Soon, makeshift shields formed from metal salvaged from the hulls of sunken ships were fitted to the carriers, which afforded better protection. But, finding that this material could be penetrated by small arms fire, subsequent shields were constructed from scrapped armored vehicles.

The ARVN 80th Ordnance Unit in South Vietnam developed the shield idea further and commenced engineering general issue gun shields for the M113. These shields became the predecessor to the standardized armored cavalry assault vehicle (or ACAV) variant and were issued to all ARVN mechanized units during the early 1960s. The ARVNs had modified the M113s to function as "amphibious light tanks" and not as battle taxis as U.S. designers had intended. Instead of an armored personnel carrier, the ARVN used the carried infantry as extra "dismountable soldiers" in "an over-sized tank crew". These "ACAV" sets were eventually adapted to U.S. Army M113s with the arrival of the army's conventional forces in 1965. The vehicles continued to operate in the role of a light tank and reconnaissance vehicle, and not as designed in theater. Still, the M113 could carry 11 infantrymen inside, with two crewmen operating it.

The U.S. Army, after berating the Vietnamese for flouting battle doctrine, came out with their own ACAV version. This more or less standardized ACAV kit included shields and a circular turret for the .50-caliber M2 machine gun in the track commander (TC) position, two M60 machine guns with shields for the left and right rear positions, and "belly armor"—steel armor bolted from the front bottom extending 1/2 to 2/3 of the way towards the bottom rear of the M113. The two rear machine gunners could fire their weapons while standing inside the rectangular open cargo hatch. This transformed the M113 into a fighting vehicle, but the vehicle still suffered from its lightly armored configuration, having never been designed for such a role. Canada also adopted the ACAV kits when employing the M113A2 during peacekeeping operations in the Balkans in the 1990s.

In order to improve the fighting ability of the mounted troops, a number of experiments were carried out in the 1960s under the MICV-65 project, which aimed to develop a true infantry fighting vehicle rather than an armored personnel carrier. Pacific Car and Foundry entered the steel-armored XM701, but this proved to be too slow and too heavy to be airmobile, even in the C-141. Food Machinery Corp. entered the XM734, which was largely the ACAV M113, but whereas the M113 seated the troops facing inward on benches along the walls, the XM734 sat them facing outwards on a central bench. Four gun ports and vision blocks were added on each side to allow the seated troops to fire even while under cover. Although neither the XM701 or XM734 were deemed worthwhile to produce, FMC continued development of their version as the XM765 advanced infantry fighting vehicle (AIFV). The AIFV was sold to a number of third party-users in the 1970s, including the Netherlands, the Philippines and Belgium.

Modifications

Modified versions of the Vietnam War ACAV sets have been deployed to Iraq (formerly referred to as "Southwest Asia" within the U.S. military) to equip the standard M113s still in service. The circular .50 caliber gun shields have been modified, while the rear port and starboard gun stations have been deleted for service in that region. Some of these modified vehicles have been utilized for convoy escort duties.

The M113 has relatively light armor, but it can be augmented with add-on steel plates for improved ballistic protection. Also, reactive armor and slat armor can be added for protection against rocket-propelled grenade. Windowed gunshields developed by an armorer in Iraq are reminiscent of ACAV vehicle modifications so effective in Southeast Asia (Vietnam War). Band tracks made of rubber are in use by Canadian and other forces to enable stealthy operation, less damage to paved roads, higher speed, less maintenance, access to terrain where operation of wheeled vehicles is impractical and less vibration and rolling resistance.

Most of the 13,000 M113s that are still in U.S. Army service have been upgraded to the A3 variant.

The M113 has also been adopted to replace the aging fleet of visually modified M551s being used to simulate Russian-made combat vehicles at the U.S. Army's National Training Center in Fort Irwin, California. These M113s, like the M551s they replaced, have also been modified to resemble enemy tanks and APCs, such as the T-80 and BMP-2. One of the advantages of the M113 being used to simulate the latter is that the infantry squad can now ride inside the simulated BMP instead of in a truck accompanying a tank masquerading as one, as was often the case with the M551s.

Nicknames

The M113 has received a variety of nicknames over the years. The South Vietnamese Army (ARVN) called it the "green dragon". United States troops tended to refer to the M113 simply as a "113" (spoken as "one-one-three"), a "track" or an "ACAV". The Israel Defense Forces employ the M113 in many different variants, all designed in Israel, and has given each of them official names, from the baseline "Bardelas" (lit. Cheetah) to the "Nagmash" (Hebrew acronym equivalent to "APC") , "Nagman", and "Kasman" variants for urban combat up to the "Zelda" and "Zelda 2", which are fitted with ERA-suites. The Australian Army refers to its M113A1s as "buckets", "bush taxis" and modified M113A1s fitted with 76 mm turrets as "beasts". The German Army has various nicknames, depending on location and branch of service, including "elephant shoe", "Tank Wedge" and "bathtub".

While some claim that the M113 has been nicknamed the "Gavin" (after General James M. Gavin), this is not an official designation. One observer said

In more than 30 years working in the defense industry, I have never, never heard anybody use the name "Gavin" for the M-113. Not in the U.S. nor in any of the many countries that use the vehicle. Not in the military forces, not in the companies that build and equip it, not in the groups that retrofit and repair it. This usage appears not only to be "unofficial", it is entirely fictional and I believe that you may have been the victim of a hoax or deliberate disinformation.

Armament

The basic M113 armored personnel carrier can be fitted with a number of weapon systems. The most common weapon fit is a single .50 caliber M2 machine gun. However, the mount can also be fitted with a 40 mm Mk 19 automatic grenade launcher. A number of anti-tank weapons could be fitted to the standard variant: the U.S. Army developed kits that allowed the M47 Dragon and BGM-71 TOW anti-tank missile systems to be mounted. In the case of the M47, the system mated to the existing machine gun mount, without having to remove the machine gun. This allowed the commander to use both weapons. A large array of turrets and fixed mounts are available to mount high explosive cannon ranging from 20 mm to 105 mm on to the M113 series, making them function as assault guns and fire support; while in many cases still having room inside to carry dismounted infantry or cavalry scouts.

Armor

The M113 is built of 5083 aircraft-quality aluminum alloy, which gives it some of the same strength as steel at a slightly reduced weight, as the greater thickness allows structural stiffness. The M113A3 was designed to provide protection against 7.62mm threat, and this proved not to be enough when tested in combat.

In comparison, modern APCs like the Stryker have an all-around 7.62mm armor-piercing protection, plus 14.5 mm protection on the front, sides, and rear. Also protection against antipersonnel mines through the vehicle floor is installed.

Mobility

Its weight allows the use of a relatively small engine to power the vehicle, a Detroit 6V53 V6 two-stroke diesel engine of 318 cubic inches (5,210 cc) with an Allison TX-100-1 three-speed automatic transmission. This allows the vehicle to carry a large payload cross-country and to be transported by fixed- and rotary-wing aircraft. Original production M113s can swim without deploying flotation curtains, using only a front-mounted trim vane; they are propelled in the water by their tracks.

Vietnam

The Vietnam War was the first combat opportunity for "mechanized" infantry, a technically new type of infantry with its roots in the armored infantry of World War II, now using the M113 armored personnel carrier. In addition, armored cavalry squadrons in Vietnam consisted largely of M113s, after replacing the intended M114 in a variety of roles, and armor battalions contained M113s within their headquarters companies, such as the maintenance section, medical section, vehicle recovery section, mortar section, and the scout (reconnaissance) section. United States Army mechanized infantry units in Vietnam were fully equipped with the M113 APC/ACAV, which consisted of one headquarters company and three line companies, normally with an authorized strength of approximately 900 men. Ten U.S. mechanized infantry battalions and one mechanized brigade were deployed to Vietnam from 1965 until their departure in 1972.

Company D, 16th Armor, 173rd Airborne Brigade was the first U.S. Army armor unit deployed to Vietnam. It originally consisted of three platoons of M113s and a platoon of self-propelled anti-tank systems (SPATS). It was the only independent armor company in the history of the U.S. Army. Upon the company's arrival in Vietnam, a fourth line platoon was added; this was equipped with M106 4.2 in. mortar carriers (modified M113s). The mortar platoon often operated with Brigade infantry units to provide indirect fire support. It also deployed at times as a dismounted infantry unit. The remaining SPATS platoon was reequipped with M113s in late 1966 and the mortar platoon was deactivated in early 1967. From early 1967, D/16th had three line platoons equipped with M113s and eventually, its diesel version, the M113A1. It also standardized in late 1968 with three machine guns per track, one M2 .50 caliber and two M60 machine guns mounted on each side. After several years, the machine gun array varied considerably from APC to APC. The company conducted search and destroy missions, road and firebase security. Twenty-five D/16th paratroopers were killed in action and many more were wounded during the course of the war. Sixteenth Division's largest battle took place on 4 March 1968 at North Tuy Hoa. "During the day, the company lost 5 men killed, 16 wounded, and 3 missing (who are believed dead as two unrecogizable (sic) bodies were found). The enemy took a much greater loss. An estimated 2 enemy battalions, 85th Main Force (VC) and the 95th NVA Regiment, were rendered ineffective as they had 297 KIAs, with d-16 Armor receiving credit for killing 218." The revised official count for D/16 was 8 KIA and 21 WIA. The company commander, Captain Robert Helmick, was awarded the DSC, and many D/16th soldiers earned awards for valor. Sixteenth Division was awarded a Meritorious Unit Award for its actions in Vietnam. It was deactivated in 1969 and the company’s M113s were distributed to E Company, 17th Cavalry, 173rd Airborne Brigade.

The M113s were instrumental in conducting Reconnaissance in force (RIFs), search and destroy missions, and large invasions (incursions) such as the U.S. invasion of Cambodia on 1 May 1970 and later Laos (Operation Lam Son 719) in 1971; all of which used the M113 as the primary work horse for moving the ground armies. While operating with cavalry and armor units, the M113s often worked in conjunction with U.S. M48 Patton and M551 Sheridan tanks. During the Vietnam War, U.S. Army gun trucks, along with V-100 armored cars, conducted convoy escorts for military traffic.

The USAF used M113 and M113A1 ACAV vehicles in USAF security police squadrons, which provided air base ground defense support in Vietnam. Also, M113s were supplied to the ARVN. One notable ARVN unit equipped with the M113 APC, the 3d Armored Cavalry Squadron, earned the Presidential Unit Citation. Additional M113s were supplied to the Cambodian Khmer National Armed Forces, equipped with a turret for the machine gun and a recoilless rifle mounted on the roof.

The Australian Army also used the M113 in Vietnam. After initial experiences showed that the crew commander was too vulnerable to fire, the Australians tried a number of different gun shields and turrets, eventually standardizing with the Cadillac-Cage T-50 turret fitted with two .30 cal Browning machine guns, or a single .30-single .50 combination. Other turrets were tried as were various gun shields, the main design of which was similar to the gun shield used on the U.S. M113 ACAV version.

In addition, the Australians operated an M113 variant fitted with a Saladin armored car turret, with a 76 mm gun as a fire support vehicle, or FSV, for infantry fire support. This has now also been removed from service.

Subsequent to Vietnam all Australian M113 troop carriers were fitted with the T50 turret. The FSV was eventually phased out and replaced with a modernized version known as an "MRV" (medium reconnaissance vehicle). The MRV featured a Scorpion turret with 76 mm gun, improved fire control, and passive night vision equipment.

Recent history

The current M113 fleet includes a mix of M113A2 and A3 variants and other derivatives equipped with the most recent RISE (reliability improvements for selected equipment) package. The standard RISE package includes an upgraded propulsion system (turbocharged engine and new transmission), greatly improved driver controls (new power brakes and conventional steering controls), external fuel tanks, and 200-amp alternator with four batteries. Additional A3 improvements include the incorporation of spall liners and provision for mounting external armor.

The future M113A3 fleet is planned to include a number of vehicles that will have high speed digital networks and data transfer systems. The M113A3 digitization program includes applying appliqué hardware, software, and installation kits and hosting them in the M113 FOV.

The U.S. Army stopped buying M113s in 2007, with 6,000 vehicles remaining in the inventory.

Israel

The Israel Defense Forces are the second largest user of the M113 after the United States, with over 6000 of the vehicles in service.

In 1967 some Jordanian M113 were captured in the West Bank and were integrated into the Israeli Army. In 1970 Israel started to receive the better armored M113A1 to replace the antiquated half-tracks. The IDF M-113s were armed with M2 HB machine guns, and two MAG 7.62 mm machine guns on either side of the upper crew compartment door. After the 1973 war armor and protection were improved. By 1982 almost all the Israeli infantry rode in Zeldas.

The M113 took part in the Yom Kippur War, in Operation Peace for Galilee, in campaigns in Lebanon, and in the West Bank and Gaza. In October 1973 the lDF was equipped with 448 M113 APCs that saw action in Golan and Sinai. They proved inadequate for direct fighting, due to their poor armor protection. In the battle of Buq'atta most of the 7th Recon Company was wiped out while trying to assault Syrian commandos with their M-113s.

In 1982 PLO ambushes with RPGs caused extensive casualties, because of the tendency of the M113’s aluminum armor to catch on fire after being hit by anti-tank weapons. In some units men became so frightened that they simply walked next to their M113 or rode outside rather than risk being burned to death. By the time of the siege of Beirut, M113s were only used to carry supplies to the front line, always stopping at least 100 meters from enemy lines. The IDF found M113s unsatisfactory for urban warfare because their machine-guns lacked sufficient elevation to use against upper stories of building, vulnerability of crew members serving machine-guns to sniper fire and difficulty to move in narrow roads and alleys of cities and refugee camps.

The Israel Defense Forces still operates large numbers of the M113 in its combat missions, from its total fleet of 6,000 of the vehicles. On numerous occasions since their introduction in the late 1960s, the IDF's M113s have proven vulnerable to modern anti-tank missiles, IEDs, and RPGs, resulting in the deaths of many Israeli soldiers riding inside the vehicles. The IDF has nonetheless been unable to replace the use of them in combat operations, due to budget constraints in equipping its large mechanized infantry regiments.

In 2004, two fully laden IDF M113s were destroyed by IEDs, resulting in the deaths of 11 soldiers, all those inside the vehicles on both occasions. The vulnerability of the M113 armored personnel carrier to IEDs and RPGs led the IDF to later begin to develop the Namer APC.

Operation Protective Edge 2014

In 2014, during the first wave of the IDF's ground incursion into Gaza during Operation Protective Edge, a Hamas RPG-29 destroyed a fully loaded M113 in Gaza, resulting in the deaths of the seven Golani Brigade soldiers riding inside the vehicle. As a result, the IDF faced calls from the Israeli public to build more Namer APCs over the next decade and to gradually reduce the number of M113s used in its future combat operations.

Israel is also prototyping the Eitan (Hebrew for steadfast), an eight-wheeled armored fighting vehicle to replace their M113s. Designed to serve alongside the tracked Namer, the Eitan is planned to be cheaper and lighter, at 35 tons, incorporating an active protection system and a turret. Field demonstrations are expected by late 2016, with initial serial production expected to begin by 2020. However, due to the slow rate of production of replacement APCs, the IDF is expected to be dependent on the M113 well into the 2020s.

Law enforcement

M113s have been adopted by numerous law enforcement agencies. An M113 belonging to the Midland County Sheriff's Department was used in the 2008 raid of the Fundamentalist Church of Jesus Christ of Latter Day Saints compound. The Osceola County, FL Sheriff's Office also uses one for its SWAT team.

The Brazilian Marine Corps's M113s were used in joint operations with Batalhão de Operações Policiais Especiais during the 2010 raid on Complexo do Alemão.

Replacement

It was the U.S Army's intention that the BCT Ground Combat Vehicle Program replace the M113 by 2018 with the GCV infantry fighting vehicle meanwhile displacing the other vehicles into task specific roles of the M113. Vehicles displaced into specific roles of the M113 would then to be replaced entirely by future variants of the GCV.

The M113 will now be replaced by the armored multi-purpose vehicle (AMPV) program. Some 2,897 vehicles in five mission roles are set to take its place at the brigade level and below within armored brigades. However, the AMPV program is not developing a vehicle to replace the M113 in supporting echelons above brigade level, which will have different requirements. BAE Systems submitted a version of the Bradley fighting vehicle for the AMPV, while General Dynamics has offered the Stryker for filling the M113's roles in rear-echelon units outside of armored brigades removed from frontline fighting, and Navistar Defense has offered an upgraded version of the Maxxpro MRAP for units above brigade level as well.

The AMPVs are to be produced at a rate of around 180 vehicles per year, enough to equip 1.3 armored brigades. With 12 brigades to modernize, the M113 is not planned be entirely replaced in armored brigades until the late 2020s. With studies on what vehicle to replace M113s with in rear-echelon units ongoing, the M113 is not likely to be phased out of U.S. Army service until after 2030, over 70 years after entering service.

Basic variants

Original version, powered by 209 hp (156 kW) Chrysler 75M V8 gasoline engine.

Starting in 1964, the gasoline engine was replaced with a 215 hp (160 kW) 6V-53 Detroit Diesel engine, to take advantage of the better fuel economy and the reduced fire hazard of the diesel engine. The suffix A1 was used on all variants to denote a diesel engine, i.e. an M106A1 was an M106 mortar carrier equipped with a diesel engine.

In 1979, further upgrades were introduced. Engine cooling was improved by switching the locations of the fan and radiator. Higher-strength torsion bars increased ground clearance, and shock absorbers reduced the effects of ground strikes. Armored fuel tanks were added externally on both sides of the rear ramp, freeing up 0.45 cubic metres (16 cu ft) of internal space. The weight of the M113A2 was increased to 11,740 kilograms (25,880 lb). Because the added weight affected its freeboard when afloat, it was no longer required to be amphibious. Four-tube smoke grenade launchers were also added. The suffix A2 is used on all variants to denote upgrade to A2 standard.

In 1987, further improvements for "enhanced (battlefield) survival" were introduced. This included a yoke for steering instead of laterals, a more powerful engine (a 6V-53T Detroit Diesel), external fuel tanks and internal spall liners for improved protection. The suffix A3 is used on all variants to denote upgrade to A3 standard.

The "armored cavalry assault vehicle" or "ACAV", was a concept and field modification pioneered by the ARVN in 1963 during the Vietnam War. The ARVN troops utilized the M113 armored personnel carrier as an infantry fighting vehicle, and more often than not, as a light tank by fighting mounted rather than as a "battle taxi" as dictated by U.S. Army doctrine.

After it was found that the commander and cargo hatch positions were extremely exposed, and hence the commander and troops were vulnerable to enemy fire, South Vietnamese engineers thought out a simple and cheap remedy to this problem: Initially, field expedient shields and mounts were made from sunken ships, but this was soft metal and could be penetrated by small arms fire. Then armor plate from scrapped armored vehicles was used; this worked well, and by the end of 1964 all ARVN ACAVs were equipped with gun shields. For the U.S. Army, ACAV sets were produced industrially in Okinawa for the 12.7 millimetres (0.50 in) machine gun, and rear aft and starboard M60 machine gun positions. Finally, the ARVN's ACAV modifications were adopted by the U.S. Army in Vietnam, and by 1965 the full ACAV set was mass-produced in the U.S. The kit included shields and circular turret armor for the commander's M2 12.7 mm machine gun, and two additional 7.62 mm M60 machine guns, again with shields, fitted on either side of the top cargo hatch. This kit could be retrofitted to any M113. ACAV sets were sometimes fitted to the M106 mortar carrier, but the different rear hatch found on this vehicle required the left M60 machine gun to be fitted to the extreme rear instead of the side. Many kits were added in the field, but at least in the case of the 11th Armored Cavalry Regiment, the vehicles had their ACAV sets installed in the U.S. prior to their deployment to Vietnam in 1966 from Fort Meade, Maryland. Additional armor in the form of a mine protective kit under the hull was also frequently fitted.

Derivatives

A smoke screen generator vehicle

A mortar carrier armed with an M30 mortar 106.7 mm (4.2 inch, or "Four-deuce") mounted on a turntable in the rear troop compartment. On this variant, the single hatch over the rear troop compartment was exchanged for a three-part circular hatch. The mortar could be fired from the vehicle, but could also be fired dismounted. Currently, the U.S. Army mortar carrier is the M106 upgraded to A3 standard and armed with an M121 120 mm mortar, a variant of the M120 mortar

Armed with an M121 120 mm mortar, a variant of the M120 mortar.

Another mortar carrier, basically an M106 armed with an M29 81 mm mortar

Variant equipped with a turret armed with a flamethrower and a .50 caliber machine gun. These vehicles are no longer used by the U.S. Army. Vehicles upgraded to A1 standard were known as "M132A1s".

Anti-tank variant equipped with a TOW ATGM launcher

Anti-aircraft variant equipped with a turret armed with a variant of the 20 mm M61 Vulcan cannon

Anti-aircraft variant equipped with a launcher armed with four MIM-72A/M48 Chaparral missiles

Unarmored cargo carrier equipped with a rear cargo bed

Command variant, the roof over the rear troop compartment is higher. The vehicle also carries additional radios and a generator. A variant of this is the M1068 standard integrated command post system carrier, equipped with the newest U.S. Army automated command and control system.

A fitter and repair vehicle equipped with a crane. This vehicle was not taken into U.S. Army service.

Repair and recovery vehicle equipped with an internal winch and two earth anchors mounted on the rear hull

Equipped with a launcher armed with two TOW missiles.

A variant of the M113 fitted with a modified Bradley turret as part of a vismod package specifically for training. This version also features MILES gear, a MGSS/TWGSS system, and fake ERA around the turret.

A lowered and shortened version of the M-113 developed for the Netherlands. It was used for reconnaissance duties with cavalry battalions and armoured engineer companies. It had four road wheels on either side. The engine was moved to the rear of the vehicle although the drive sprockets were maintained at the front. Armament was a 25 mm cannon in a remotely operated turret. Crew consisted of commander, driver and gunner. It has also been used by the Canadian Army as 'Lynx reconnaissance vehicle'.

A development of the M113A1 APC, upgraded with an enclosed turret and firing ports.

A huge number of M113 variants have been created, ranging from infantry carriers to nuclear missile carriers. The M113 has become one of the most prolific armored vehicles of the second half of the 20th century, and continues to serve with armies around the world into the 21st century. Not without its faults, the otherwise versatile chassis of the M113 has been used to create almost every type of vehicle imaginable. Few vehicles ever created can claim the application to such a wide range of roles.

In 1994, a stretched version of the M113 was presented by its manufacturer, also known as "mobile tactical vehicle light" (MTVL). Its hull is lengthened by 34 inches and equipped with an additional road wheel (six on each side) to sustain the added dry weight and payload. The vehicle was developed as a "production-tooled demonstrator" with private-industry funding from United Defense. Although the U.S. Army did not buy it, it was acquired by other nations, and is copied today by Pakistan, Turkey and Egypt in their local M113-producing plants. Some nations, like Canada and Australia, also stretched existing M113-hulls.

Several countries acquired M113s and later copied the design and proceeded to produce clones or evolved models (post-M113A3-standard) in their own indigenous factories. Pakistan produces an armored personnel carrier known as Talha which has a number of mechanical and automotive parts in common with the M113. Turkey produces the ACV-300 based on the AIFV. Egypt produces many variants of the M113A4 incl. the Egyptian infantry fighting vehicle (EIFV), which features a combination of an M113A3-base and the fully functional and stabilized two-man turret of the M2 Bradley. Iran is also producing its own M113s.

Former operators

Civilian operators

Evaluation-only operators