M8 Armored Gun System

M8 Armored Gun System
Type - Light tank
Place of origin - United States
Production history
Designer - FMC Corporation/United Defense LP
Designed - From 1983
Manufacturer - United Defense LP/BAE Systems
Produced - 1995, 2020
No. built - 6 AGS pilots, 12 Mobile Protected Firepower
Specifications (M8 AGS)
Mass - 36,900 to 39,800 lb (16,740 to 18,050 kg) (level 1 armor) / 44,000 to 44,270 lb (19,960 to 20,080 kg) (level 2) / 52,000 lb (23,590 kg) (level 3)
Length - 261.4 in (6.64 m) (Level 1 hull + gun forward), 241.9 in (6.14 m) (Level 1 hull only)
Width - 104 in (2.64 m) (over fenders)
Height - 100 to 101 in (2.5 to 2.6 m) (over cupola)
Crew - 3 (commander, gunner, driver)
Elevation - +20° / -10° (depression limited over rear arc)
Armor - Welded 5083 aluminium alloy
Main armament - M35 105 mm caliber soft recoil rifled gun (31 rounds)
Secondary armament - 7.62 mm coaxial M240 (4,500 rounds) / 12.7 mm commander's M2 Browning (600 rounds)
Engine - Detroit Diesel Corporation 6V 92TA / 550 hp (410 kW) at 2,400 rpm (JP-8 fuel) . 580 hp (430 kW) at 2,400 rpm (diesel)
Power/weight - 28.3 hp/ST (23.3 kW/t) (Level I)
Transmission - General Electric HMPT-500-3EC
Suspension - Torsion bar
Ground clearance - Up to 17 in (430 mm)
Fuel capacity - 150 US gal (570 l; 120 imp gal)
Operational range - 300 mi (480 km)
Maximum speed - Road: 45 mph (72 km/h)

Tanks of the United States
World War I: Mark VIII tank / Ford 3-Ton M1918 / Holt gas electric tank / M1917 light tank / Renault FT
Interwar: Medium Tank M1921 / Medium Tank M1922 / T1 Light Tank / T2 Medium / M1 Combat Car / M2 light tank / Christie M1931
World War II - 
M2 medium tank / M3/M5 Light Tank / M3 Lee / M4 Sherman / M22 Locust / M24 Chaffee / Marmon-Herrington CTLS / M26 Pershing
Cold War: M41 Walker Bulldog / M46 Patton / M103 / T57 / T110 / M47 Patton / M48 Patton / T95 Medium Tank / M60 tank / T92 Light Tank / M551 Sheridan / MBT-70 / XM803 / Expeditionary tank / M1 Abrams / M8 Armored Gun System / Block III tank
Post-Cold War period: Mobile Protected Firepower

The M8 Armored Gun System (AGS), sometimes known as the Buford, is an American light tank that was intended to replace the M551 Sheridan and TOW missile-armed Humvees in the 82nd Airborne Division and 2nd Armored Cavalry Regiment (2nd ACR) of the U.S. Army respectively.
The M8 AGS began as a private venture of FMC Corporation, called the Close Combat Vehicle Light (CCVL), in 1983. The Army began the Armored Gun System program to develop a mobile gun platform that could be airdropped. By 1992, the AGS was one of the Army's top priority acquisition programs. The service selected FMC's CCVL over proposals from three other teams. The service sought to purchase 300 AGS systems to begin fielding in 1997.
The Army canceled the M8 AGS program in 1996 over the objections of Congress and the Department of Defense, due to the service's budgetary constraints. The Sheridan was retired without a true successor. The AGS never saw service, though the 82nd Airborne sought to press a limited number into service in Iraq. The AGS was unsuccessfully marketed for export, and was reincarnated for several subsequent U.S. Army assault gun/light tank programs. United Defense LP proposed the AGS as the Mobile Gun System (MGS) variant of the Interim Armored Vehicle program in 2000, but lost out to the General Motors-General Dynamics' LAV III, which was type classified as the Stryker M1128 Mobile Gun System. BAE Systems offered the AGS system for the Army's Mobile Protected Firepower requirement, but lost to the General Dynamics Griffin in 2022.
Development
The Army recognized the poor performance of the M551 Sheridan light tank in Vietnam and, in 1977, began the process of retiring the vehicle. A small number were retained in active service by the 82nd Airborne Division and the National Guard. The Army designated the M3 Bradley cavalry fighting vehicle to partially fill the Sheridan's role.
In the 1980s, the United States Army began looking for a more capable replacement for the Sheridan. During this time, a string of Army projects to update or replace the Sheridan were begun, but all ended without the Army committing to buy. Some of its efforts around this time could be described as hopelessly intermingled.
In 1979, Army Chief of Staff General Edward C. Meyer initiated a transformation of the 9th Infantry Division that would see the light infantry division assume many of the characteristics of the heavy division through an infusion of high or emerging technology. The so-called "High Technology Light Division" would require the procurement of a Mobile Protected Gun, later called the Assault Gun System (AGS), and a Fast Attack Vehicle. The notional Mobile Protected Gun was to be armed with a kinetic gun, or possibly a missile, capable of defeating enemy armor. In any case, the service determined that it needed a more immediate solution for the AGS requirement. In 1985, the Army approved a U.S. Army Training and Doctrine Command (TRADOC) recommendation to field the TOW missile-armed Humvee in the interim. The TOW-armed Humvee proved to be an inadequate substitute for the AGS in the 9th Infantry Division as it could not fire on the move and was too lightly armored.
In 1980, the U.S. Army Infantry School's Mobile Protected Gun project analyzed anti-armor weapons systems, concluding that the Army should equip its new light infantry divisions with TOW-armed Humvees and an unspecified 6×6 lightly armored vehicle armed with a 25 mm caliber gun. This led the Secretary of Defense to direct the Army to use the LAV-25 for this purpose. In 1981, the Army joined the Marine Corps's Mobile Protected Gun System program. The MPGS was canceled the following year. The basic chassis of the Sheridan was considered to be in good working order even if its problematic 152 mm caliber gun/launcher was not. Both the Marine Corps and Army explored re-gunning the Sheridan with a conventional gun. In 1983, the Naval Surface Weapons Center mounted a 105 mm cannon to a Sheridan. One Army plan also envisioned re-gunning a few dozen Sheridan with 105 mm or 120 mm cannons, but this project was canceled in 1985.
After the cancelation of the MPGS program, the project morphed into the Armored/Assault Gun System. In 1983, the Army established the AGS program. In 1985, Army Vice Chief of Staff General Maxwell Thurman approved an amended Requirement Operational Capability (ROC) for the Armored Gun System. Thurman recommended that the Army purchase 500 AGS systems. The Army Chief of Staff did not advocate for funding the program in Congress, however, given its low priority. Senate appropriators declined the Army's request for AGS funds for FY1986. The program office was disestablished, and the ROC retracted. In May 1986, the AGS program was re-organized under the Armored Family of Vehicles Task Force (AFVTV). During one concept study for a proposed All Purpose Fire Support Platoon, the task force shortlisted four candidate vehicles for an Armored Support Platform. These were the FMC Corporation Close Combat Vehicle Light (CCVL), the Cadillac Gage Stingray, the General Motors LAV-105, and the Teledyne AGS. The task force recommended the latter.
In 1987, the Army tested a version of the LAV-25, designated as the M1047. The Army determined that these were unsuitable for LAPES, and with only a 25 mm caliber cannon, could not match the firepower of the Sheridan. Congress did not favor the M1047, though a few were deployed with the 3/73rd Armor of the 82nd Airborne Division in the Gulf War.
In August 1987, the Office of the Secretary of Defense approved the AGS program initiative for 600 vehicles. A joint Army-Marine Corps program was mooted. The ROC was approved for the second time in September. In December, the AGS program was dropped as the $800 million ($1.91 billion in 2021) plan was considered unaffordable. Around the same time, the Army Chief of Staff issued a "promissory note" to replace the Sheridan by FY1995.
In September 1989, the Armored Gun System Project Manager office was reestablished at the United States Army Tank-automotive and Armaments Command and a marketing survey was distributed to industry. The Army formalized the AGS program in April 1990 with the issue of a new ROC.
In November 1990, the Defense Acquisition Board authorized the Army to proceed with development of the AGS. The Army believed that replacing the Sheridan with an off-the-shelf AGS would be less expensive and provide more capabilities than an upgraded Sheridan. In addition to being expected to replace the Sheridan in the 3/73rd Armor, it was to replace TOW missile-armed Humvees in the 2nd Armored Cavalry Regiment (2nd ACR).
In 1991, the Senate and House Armed Services Committees joined in directing the Army to integrate the turret and Watervliet Arsenal EX35 gun of the LAV-105 with an AGS chassis. A joint program was balked at by both services, who believed the two platforms were mismatched. Subsequently, the Marine Corps demurred and requested no further funding for the LAV-105. In any event, the proposed chimera was nixed by the Senate Appropriations Committee later that year.
The AGS program had gathered steam by this point due in part to the back-to-back successful employment of the Sheridan in two overseas operations. In December 1989, Sheridans of the 3/73 Armor were airdropped into Panama as part of Operation Just Cause. This was the first successful employment of light armor in combat. In August 1990, Sheridans were airdropped into Saudi Arabia as the spearhead of the buildup of Operation Desert Shield.
The Army issued a draft request for proposals (RfP) in May 1991. The Army published the RfP in August incorporating changes as a result of feedback from industry and Congress, the latter of which had directed the Army to require the EX35 gun. Army Acquisition Executive Stephen K. Conver became concerned that the AGS program was becoming laden with unnecessary requirements that would increase costs and development time, as well as limit the number of interested contractors. In view of this, in October 1991, Conver's office conducted a review of the requirements. The Army updated its RfP later that year, with submissions due in December. Following the deferment of the RAH-66 Comanche and Block III tank, the AGS was among the Army's top priority programs. After having earlier tried to kill the tank, appropriators grew to appreciate the program's relatively low price tag.
FMC Corporation submitted the Close Combat Vehicle Light to meet the AGS requirement.
Three other teams submitted proposals:
General Dynamics Land Systems and Teledyne Continental Motors submitted a version of the Teledyne tank included in the AFVTV study. This was an unconventional design with a low-profile turret and the crew located in the hull.
Cadillac Gage Textron submitted the Commando Stingray with the LAV-105 turret.
Team Hägglunds USA submitted a variant of the Combat Vehicle 90 with a GIAT turret.
In June 1992, the Army selected the FMC proposal. FMC was awarded $27.7 million ($53.5 million in 2021) to begin phase 1 work, including the production of six test units. The bids for this phase ranged from a high of $189 million ($365 million in 2021) for GDLS-Teledyne and a low of $92 million ($178 million in 2021) for Hägglunds. The procurement program was valued at $800 million.
The Close Combat Vehicle Light becomes the AGS
A black and white photo of an AGS sits in an open field. An M2 Browning machine gun is mounted at the commander's station.
FMC began developing the Close Combat Vehicle Light as a private venture in 1983. The vehicle was designed from the outset to meet the Army's as-yet unfunded Armored Gun System requirement. FMC built two mock-ups. The first was a front-engine model utilizing a 330 hp (250 kW) diesel engine. The second was a rear-engine model with a 552 hp (412 kW) diesel engine and featuring more armor. In 1984, FMC validated the feasibility of pairing the 105 mm gun with a light chassis by test firing a 105 mm gun mounted on an M548. The first prototype CCVL was completed in August 1985 and debuted at the meeting of the Association of the United States Army in October. The CCVL was demonstrated at Fort Bragg in 1987.
The Army did not originally require that the AGS be air-droppable by the C-130, believing that the requirement would deter submissions. Nevertheless, FMC's proposal claimed that this desired capability was possible with its design. After winning the contract, FMC made several weight-saving changes to the design, particularly the pallets, in order to meet the C-130's weight limit.
In a December 1993 report, the Defense Department Inspector General cautioned that the AGS would be too heavy for low-velocity airdrop. The report said the AGS did not meet the Army's requirements for air mobility, and recommended delaying low-rate initial production until the airdrop requirement could be met. The Army strongly refuted the IG's report. The IG's concerns were put to rest in October 1994, when the service successfully airdropped an AGS from a C-130 at an altitude of 1300 feet.
Citing cuts in procurement funding, in 1993, the Army cut its planned AGS order from 300 to 233. In 1994, the Army settled on an acquisition target of 237 vehicles. Of these, 123 would go to the 2nd Armored Cavalry Regiment, 58 to the 82nd, and 56 to reserves and training bases. The last 169 AGS systems, to be produced from 1998 to 2002, were to be built without the weight-saving modifications of those destined for the 82nd, which was the only unit that required an airdroppable AGS system.
Six prototypes were built under the designation XM8. The first of these was rolled out at the United Defense (created by a merger of FMC and BMY) facility in San Jose, California, in April 1994, and arrived at Fort Knox, Kentucky, in April 1995. The last of these was delivered in May. United Defense provided five XM8 AGS systems to the service's Operational Test Command, which put the vehicle through five months of testing at Fort Pickett, Virginia. Another prototype underwent survivability testing at Aberdeen Proving Ground, Maryland.
In 1995, the Army explored cutting the 2nd ACR, which would reduce the Army's buy to 80 AGS for the 82nd Airborne. In May 1995, the National Guard expressed interest in procuring the AGS for the 38th Infantry Division, 35th Infantry Division and 34th Infantry Division in order to help bridge the looming capability gap should the 2nd ACR be eliminated. This proposal was rejected by the service. In October 1995, the Army type classified the XM8 as the M8 Armored Gun System. It approved an initial production run of 26 vehicles, with an option for 42 more scheduled to begin in FY1997. A full production decision would be reached in 1997. Fielding to the 3/73 Armor would begin in 1999. All three squadrons of the 2nd ACR were to be fielded subsequently.

Cancelation

AGS production schedule as of 1995
Year - Orders - Deliveries
1996 - 26 - 0
1997 - 42 - 4
1998 - 33 - 31
1999 - 40 - 40
2000 - 40 - 35
2001 - 35 - 40
2002 - 21 - 39
2003 - nil - 36
2004 - nil - 12

The end of the Cold War had precipitated a fall-off in U.S. military spending. The President's FY1996 budget request allotted the Department of Defense (DoD) the lowest procurement budget level since 1950. The AGS was one of several systems that did not fare well in an Army review of anti-armor weapons then under development. Responding to budget cuts anticipated in the period FY98-03, in 1996 the Army adopted a new policy: Instead of distributing small cuts throughout many projects, entire programs would be canceled. Army Chief of Staff Dennis Reimer canceled the AGS in January 1996.
Many officials felt blindsided by the Army's decision to kill the AGS. The Army's decision to cancel the AGS lacked a formal announcement, but was soon leaked to the press. This displeased some lawmakers including Senate Armed Services Committee chairman Strom Thurmond, who privately expressed irritation to Defense Secretary William J. Perry about having learned of the cancelation through media reports.
Ten Representatives signed a letter urging Perry to continue on with the program. The letter touted the program's "tremendous success" in meeting the program's objectives, and noted that the vehicle was "well within budget and on schedule". The House appropriations national security subcommittee requested that the DoD pause the cancelation of the AGS pending a Congressional review. The subcommittee said that the AGS had met its milestones and "would be a strong candidate for increased funding".
The Army belatedly sought to win Congressional and DoD support for its decision to cancel the tank. Securing the blessings of the Office of the Secretary of Defense would ensure that the service would not have to forfeit unspent FY1996 funds from the AGS program. The DoD, at least at first, affirmed its support for the program and called it "premature" for any service branch to draw any conclusions about the outyear funding environment. However, in February the Joint Requirements Oversight Council (JROC) endorsed the Army's decision. Despite JROC's recommendation, Perry withheld his support for canceling the AGS until he could personally meet with key congressmen. Perry's office said it would review the Army's plans for the $1 billion originally earmarked for the AGS before making a decision.
The Army issued a stop-work order to United Defense in February. In May 1996, the Army Vice Chief of Staff formally announced the cancelation of the AGS. The service estimated killing the program would save the Army $1 billion. The service sought to reallocate unspent FY1996 funds from the AGS program on military pay, construction and modernization programs.
In order to help offset the loss of capability caused by the cancelation of the AGS, the Army increased its requested funding for M1A2 Abrams and M2A3 Bradley upgrades, and accelerated the development of the Javelin missile. The Army considered a variety of plans to "heavy up" the 2nd ACR. The service added heavy armor to the 2nd ACR and requested funding to purchase Apache helicopters. In the 82nd Airborne, the Army also planned to introduce the EFOGM missile and considered more widely fielding the Javelin missile. Funding for EFOGM was deleted in 1998. The Army also considered the Humvee-mounted MGM-166 LOSAT missile, another platform offering similar capabilities for the 82nd Airborne. However, this program was canceled in FY2005.
The 3/73rd Armor was inactivated over the following two years. The last Sheridans in service were vismod Sheridans used for opposing force training. These too were retired in 2004. Maintaining the Sheridan was not thought to be practical. In place of the Sheridan in the 82nd Airborne, the Army stood up an Immediate Ready Company of Bradley Fighting Vehicles and M1A1 Abrams tanks from the 3rd Infantry Division which were to be attached to the 82nd.
Proposed revivals
In 1998, the Senate Armed Services Committee proposed using the M8 AGS as a surrogate vehicle to evaluate "strike force experimentation activities" in the 2nd Cavalry Regiment.
United Defense LP (UDLP) proposed the AGS, as well as a version of the Mobile Tactical Vehicle Light, for the Mobile Gun System variant of the Interim Armored Vehicle program in 2000. United Defense provided an AGS armored in level 1 and 2 for a platform performance demonstration from December 1999 to January 2000. By then, the AGS had reached an advanced level of technological maturity, and thus UDLP said it could field its design almost two years earlier than the General Motors' LAV III proposal. The AGS lost out to the General Motors proposal, which was type classified as the Stryker M1128 Mobile Gun System. UDLP protested the award, alleging that the Army disregarded its own timeline requirements, and that the requirements had been crafted with a wheeled vehicle in mind. The General Accounting Office denied UDLP's protest in April 2001.
In March 2004, at the 82nd Airborne Division's request, the Army approved the transfer of four production vehicles from United Defense's facility in Pennsylvania to Fort Bragg, North Carolina. The vehicles were intended to bolster the 82nd's 17th Cavalry Squadron, which was in need of greater firepower for an upcoming deployment to Iraq. However, in June 2004, this plan was put on hold while the Army determined whether the Mobile Gun System (MGS) could meet the 82nd's requirements. An air-drop test of a Stryker weighted to simulate the load of the MGS was conducted in August. Around the same time, the Army identified issues with the air-worthiness of the MGS, among the heavier of the Stryker family. Still more pervasive problems persisted with the autoloader. While this decision was on hold, Congressman Robin Hayes expressed frustration that the AGS had not been fielded, and called on the Department of Defense to act swiftly to resolve the delay. In January 2005, the Army said it had ruled out fielding the AGS, saying the system lacked spare parts that would be required to maintain the vehicle for any significant length of time. The Army also doubled down on its commitment to fielding the MGS, which it said it could begin fielding in summer 2006.
United Defense sought overseas customers without success. In 1994 United Defense partnered with Rheinmetall to market the AGS to NATO allies. Taiwan had been interested in acquiring as many as 700 of the system, which would be produced domestically. In 1994, the U.S. State Department authorized the sale of just as many to Taiwan and Hwa Fong Industries of Taiwan and United Defense agreed to co-production conditional on the selection of vehicle by Taiwan. In 1996, United Defense had plans to ship one AGS prototype to Taiwan. In 1996, United Defense partnered with FMC Nurol to offer the AGS to the Turkish Land Forces, which was seeking a main battle tank. By 1998, Canada, Germany, Malaysia and Singapore had expressed interest in the tank.
In 2015, the U.S. Army articulated a requirement for a Mobile Protected Firepower system to replace the Mobile Gun System. In 2017, the Army formalized its requirements with a request for proposals. The MPF was defined as an air-transportable light tank to assist infantry brigades in forced entry operations. The Army sought to buy 504 MPF systems. Requirements called for a tracked vehicle armed with a 105 mm or 120 mm caliber cannon, which would not need to be air-droppable. BAE Systems (which bought United Defense in 2005) entered a modernized AGS into the MPF competition. In 2018, the Army selected bids from GDLS and BAE to build 12 prototypes each. BAE began delivering the prototype vehicles to the Army in December 2020, although the last of these were delivered behind schedule after testing had begun. The Army's evaluation of BAE and General Dynamics prototypes at Fort Bragg continued through August. In February 2022, BAE was eliminated from the competition due to noncompliance issues, leaving the General Dynamics Griffin as the only MPF entry. In June 2022, the Army selected the Griffin as the winner of the MPF competition.
Design
The basic hull of the AGS is made of welded 5083 aluminium alloy, with a modular armor system that allows the vehicle to be equipped according to requirements. Aluminum was chosen instead of steel in order to reduce the weight of the vehicle. The weight limit for the vehicle was driven by the requirement that it be capable of low-velocity airdrop (LVAD).
Protection
The CCVL hull was all-welded aluminum with bolt-on steel composite armor. Appliqué armor could also be installed by the user.
The AGS was designed with three modular armor levels:
The Level I (basic) armor package consisted of ceramic armor tiles and protected the vehicle against small-arms fire and shell splinters. It was designed for the rapid deployment role and could be airdropped from a C-130. All-up weight was 39,800 lb (18,100 kg).
The Level II armor package consisted of additional plates of titanium, hardened steel and expanded metal. At an all-up weight of 44,270 lb (20,081 kg), Level II-armored AGS could still be carried by C-130, but could not be air-dropped.
Level III armor consisted of bolt-on armor boxes, and is designed for contingency operations and provides protection against light handheld anti-tank weapons. Level III-armored AGS systems cannot be carried by C-130. All-up weight is 52,000 lb (24,000 kg).
The crew is protected from ammunition explosion by blowout panels on the roof and a bulkhead separating the ammunition from the crew. Unlike the CCVL, the AGS is equipped with NBC overpressure system. The Army omitted a requirement for radiation hardening from the AGS.
Two eight-barrel smoke grenade launchers were mounted to the turret which could fire a variety of obscurants.
The United Defense Mobile Gun System variant included 7.62 mm integral armor protection over most of the vehicle, and 14.5 mm AP protection over the frontal 60-degree arc. BAE equipped the Mobile Protected Firepower variant of the AGS with underbody blast protection from roadside bombs.
Mobility
Power is provided by a Detroit Diesel 6V-92TA 6-cylinder multifuel diesel engine developing 550 hp (410 kW) at 2400 rpm with JP-8 fuel, and 580 hp (430 kW) at 2400 rpm with DF2 diesel. This had 65% commonality with the eight-cylinder version of the Heavy Expanded Mobility Tactical Truck (HEMTT). The AGS's power-to-weight ratio was greater than the M1A1 Abrams. The top speed is governor-limited to 45 mph (72 km/h). The fuel capacity is 150 US gal (570 l; 120 imp gal), giving the AGS a projected range of 300 mi (480 km) at a cruising speed of 25 mph (40 km/h). The General Electric hydromechanical HMPT-500 transmission is also used by the Bradley Fighting Vehicle. Mounted on two tracks, the powerpack slides out for maintenance, and can be run while it sits on the tracks at the rear of the vehicle. An auxiliary power unit was considered, but ultimately omitted from the final design to save weight.
Many different engines, including a gas turbine, were considered for follow-on versions of the CCVL. The Detroit Diesel engine was replaced in the Mobile Protected Firepower variant with an unspecified model, this one also developing 550 hp (410 kW).
FMC designed the CCVL with to be capable LAPES (low-altitude parachute-extraction system) airdrop from a C-130. The Army required two variants of the AGS. One capable of the low-velocity airdrop from the C-17 Globemaster III (intended for the 82nd Airborne), and a heavier variant with roll-on/roll-off capability from the C-5 Galaxy, C-17, C-141 Starlifter and C-130 Hercules. In 1990, the Army had demoted the requirement for LAPES from a required capability to a desired one. After winning the AGS contract, FMC further whittled down the weight of the AGS in order make the tank light enough for low-velocity airdrop from a C-130.
Level II and III armor packages can be airdropped separately from the AGS and installed in the field in under three hours. All versions are air-transportable by C-130, C-141, C-17 and C-5 (one, two, three and five systems respectively). For low-velocity airdrop, the vehicle is stripped to a weight of no more than 17.8 short tons (16.1 t). The vehicle height is reduced by removing or retracting the commander's cupola. Up to 10 rounds of 105 mm ammunition can be carried in ready capacity. The MPF variant retained airlift capability: one could fit on the C-130 and three on the C-17.
A 1993 TRADOC study called for modifying 53 HEMTTs as Contingency Force Recovery Vehicles to assist with recovering the AGS.
Firepower
The AGS is armed with the Watervliet Arsenal M35 (rifled autoloading 105 mm caliber soft-recoil tank gun with an M240 7.62 mm caliber machine gun mounted coaxially.
The M35, known as the EX35 and XM35 during development, was originally designed and developed by Benét Laboratories, Watervliet Arsenal in 1983 for the Marine Corps Mobile Protected Gun Program. The M35 is about 1,800 lb (816 kg) lighter than the M68 used on the M60 tank.
The M35 fires all NATO standard 105 mm ammunition in inventory. The M35 has a rate of fire of approximately 12 rounds per minute, with a ready capacity of 21 rounds and 9 more in hull stowage. It has a laser rangefinder from the M1 Abrams, and the Computing Devices Canada fire-control system is the same used in the Challenger 2. Prototype versions of the AGS gun had a pepperpot muzzle brake which was anticipated would be deleted in the production version.
The gun is stabilized with a Cadillac Gage two-axis system. Gun depression and traverse is hydraulic, with a manual back up for emergencies. Depression and elevation is -10 degrees, except over a rear 60 degree arc, where it is limited to 0 degrees.
The CCVL was originally armed with Rheinmetall's soft-recoil version of the M68A1. It held 19 ready rounds, plus 24 in hull storage.
The autoloader is fed by a rotating 21-round magazine. The gunner selects the type of ammunition to be fired and the computer rotates the magazine to select the correct round accordingly. Automatic and single-shot modes are available. After firing, the gun returns to zero degrees elevation. The autoloader extracts the spent shell casing from the breech, then ejects the casing out of the turret through the same port used to load the autoloader. Once the autoloader has loaded the next round, the gun returns to the elevation of the last target. If the autoloader is disabled, the crew can load the AGS under armor at a rate of three rounds per minute.
The gunner Hughes day/night thermal sight was stabilized. The CCVL had a commander's independent thermal viewer, but this was later eliminated to save weight.
The M35 fires all NATO-standard 105 mm caliber ammunition. The planned targets for the AGS ranged from bunkers and other man-made structures to armored personnel carriers and light armored vehicles. The AGS has the potential to engage main battle tanks, but these more heavily armored vehicles are less likely to be the AGS's main targets.
A Browning M2 12.7 mm (.50) caliber heavy machine gun is mounted in a manually operated pintle on the commander's hatch. Other possible weapons were a M240 7.62 mm caliber machine gun or an MK 19 40 mm grenade launcher.
Miscellany
The AGS has a 1553 data bus. This is not present in the CCVL.

Comparison of tanks
_ - CCVL - M8 AGS - Vickers/FMC Mk 5 - M551A1 Sheridan (TTS) - M1A1 Abrams
Hull Length - 244 in (6.197 m) - 242 to 247 in (6.1 to 6.3 m) - 244 in (6.2 m) - 248 in (6.3 m) - 312 in (7.9 m)
Width - 106 in (2.692 m) - 104 in (2.6 m) (over fenders) - 106 in (2.69 m) - 110 in (2.8 m) - 144 in (3.7 m)
Height - 92 in (2.349 m) (turret roof) - 100 to 101 in (2.5 to 2.6 m) (over cupola) - 103 in (2.62 m) (overall) - 116 in (2.9 m) (over MG) - 114 in (2.9 m) (over MG)
Ground Clearance - 16 in (0.406 m) - 15 to 17 in (38.1 to 43.2 cm) - 16 in (0.41 m) - 19 in (48.3 cm) - 19 in (48.3 cm)
Top Speed - 43 mph (70 km/h) - 45 mph (72 km/h) - 43 mph (70 km/h) - 43 mph (69 km/h) - 41.5 mph (67 km/h)
Fording - 52 in (1.32 m) - 40 in (1.0 m) - 39 in (1.0 m) - Floats - 48 in (1.2 m) (w/o kit)
Max Grade - 60 percent - 60 percent - 60 percent - 60 percent - 60 percent
Max Trench - 7 ft 0 in (2.133 m) - 7 ft (2.1 m) - 7 ft 0 in (2.13 m) - 8 ft (2.4 m) - 9 ft (2.7 m)
Max Wall - 30 in (0.762 m) - 32 in (0.8 m) - 30 in (0.76 m) - 33 in (0.8 m) - 49 in (1.2 m)
Range - 300 mi (480 km) - 300 mi (480 km) - 300 mi (480 km) - 350 mi (560 km) - 289 mi (465 km)
Power - 575 hp (429 kW) at 2400 rpm - 550 hp (410 kW) at 2400 rpm (JP-8) - 552 hp (412 kW) at 2300 rpm - 300 hp (220 kW) at 2800 rpm - 1,500 hp (1,100 kW) at 3000 rpm
Power-to-Weight Ratio - 24.2 hp/ST (26.7 hp/t) - 28.3 to 21.2 hp/ST (23.3 to 17.4 kW/t) - 25.4 hp/ST (28 hp/t) - 17.9 hp/ST (14.7 kW/t) - 23.1 hp/ST (19.0 kW/t)
Torque - N/A - 1,446 lb⋅ft (1,960 N⋅m) at 1500 rpm - N/A - 615 lb⋅ft (830 N⋅m) at 2100 rpm - 3,934 lb⋅ft (5,330 N⋅m) at 1000 rpm
Weight, Combat Loaded - 42,801 lb (19,414 kg) - 36,900 to 52,000 lb (16,740 to 23,590 kg) - 43,541 lb (19,750 kg) - 33,600 lb (15,240 kg) - 130,000 lb (58,970 kg)
Ground Pressure - 9.81 psi (0.69 kg/cm2) - 9.1 to 12.2 psi (0.64 to 0.86 kg/cm2) - 9.8 psi (0.69 kg/cm2) - 6.9 psi (0.49 kg/cm2) - 14.4 psi (1.01 kg/cm2)
Main Armament - M68A1 105 mm gun - M35 105 mm rifled - 105 mm low recoil force gun - M81E1 rifled 152 mm gun/launcher - 120 mm M256 smoothbore
Elevation - +20° / -10° (limited depression over rear arc) - +20° / -10° (limited depression over rear arc) - +20° / -10° (limited depression over rear arc) - +19.5° / -8° - +20° / -10°
Traverse Rate - N/A - 8.5 seconds/360° - 9 seconds/360° - 10 seconds/360° - 9 seconds/360°
Elevation Rate - N/A - 11°/second - N/A - 4°/second - 25°/second
Main Gun Ammo - 43 (19 ready) - 30 (21 ready) - 41 (19 ready) - 29 (including 9 missiles) - 40
Firing Rate - 12 rds/minute - 12 rds/minute - N/A - 4rds/minute - 6rds/minute
Crew - 3 (commander, gunner, driver) - 3 (commander, gunner, driver) - 4 (commander, gunner, loader, driver) - 4 (commander, gunner, loader, driver) - 4 (commander, gunner, loader, driver)
Protection - All-welded aluminum hull and turret with bolt on steel composite armor - 5083 aluminium alloy hull, armor arrays-reinforced turret - Aluminum hull and turret with applique steel plates - 7039 aluminium alloy hull, rolled homogeneous steel turret - Rolled homogenous steel, with armor arrays in turret and hull

Variants

Close Combat Vehicle Light
FMC began developing the Close Combat Vehicle Light as a private venture in 1983. The first prototype CCVL was completed in August 1985 and debuted at the meeting of the Association of the United States Army in October.
M8 Armored Gun System
The AGS eliminated the commander's independent thermal viewer of the CCVL. The Watervliet Arsenal M35 replaced the M68A1 gun.
Vickers/FMC Mark 5 battle tank
In 1985 the British Vickers Defence Systems and FMC collaborated on a derivative of the CCVL intended for export customers. The prototype was completed in May 1986 and first publicly appeared later that year. The tank had a fourth crewmember in lieu of an autoloader. It was armed with a 105 mm low recoil force gun, and could accept a number of other 105 mm guns as well.
A woodland camouflaged AGS LOSAT system fires a missile. A backblast emanates from the rear of the turret. The turret appears more boxy than the original AGS turret.
Line of Sight Anti-Tank (LOSAT)
In 1994, Loral Vought Systems was awarded a contract worth up to $42.5 million ($77.7 million in 2021) to integrate the LOSAT missile onto an AGS chassis. In lieu of the turret, a missile pod with 12 kinetic energy missiles was installed. At least one full-scale mockup of the AGS LOSAT had been constructed by 1995. Delivery of the AGS LOSAT was scheduled for 1996. After the cancelation of the AGS, the Army switched the chassis of the LOSAT to the Humvee.
M8 Enhanced Capabilities Demonstrator/Thunderbolt
A single technology demonstrator built by United Defense and demonstrated in 2003. The ECD had a hybrid electric drive instead of a diesel engine. The tracks were a rubber band type. Armament was an XM291 120 mm electrothermal-chemical smoothbore cannon fitted with an autoloader. A storage area in the rear could be used to carry up to four crew members or other equipment, such as additional ammunition.
Lightning Bolt
In August 2004, BAE conducted live fire testing of the Lightning Bolt at Camp Roberts, California. Like the ECD, the Lightning Bolt incorporated a hybrid electric drive and XM291.
120 Armored Gun System
BAE Systems debuted the AGS 120 in 2006. The chassis was based on the original M8 AGS but integrated the 120 mm gun and turret of the ECD/Thunderbolt.
Mobile Protected Firepower
BAE Systems entered an updated variant of the M8 in the U.S. Army Mobile Protected Firepower program. According to BAE, the MPF variant is completely redesigned, keeping only the footprint (length, width and height). The MPF incorporates a new transmission and MTU powerpack, band composite rubber track and a new fire-control system. BAE added improved underbody armor, as well as the Iron Fist active protection system and BAE's Terra Raven soft-kill system.
Singapore design study
In 2004, United Defense and Singapore studied using the AGS to meet Singapore's requirement for a replacement for its AMX-13 SM1 light tanks. In addition to a Thunderbolt-derived AGS variant, United Defense submitted a number of designs that mounted the Thunderbolt AGS's 120 mm cannon/turret (and alternatively, 105 mm) on a variety of chassis. These chassis were the Bionix IFV and the Universal Combat Vehicle Platform that the Primus self-propelled howitzer was based on.

General Dynamics Griffin II
2S25 Sprut-SD, Russian airborne light tank
XM1202 Mounted Combat System, a U.S. Army tank, that was part of the Future Combat Systems Manned Ground Vehicles program cancelled in 2011
Mobile Gun System, a U.S. Army assault gun acquisition program (part of the Interim Armored Vehicle program), in which the AGS took part
Mobile Protected Firepower, ongoing U.S. Army light tank acquisition program, in which the AGS is taking part
Future Scout and Cavalry System/TRACER, a joint UK-U.S. scout vehicle canceled in 2001