Key characteristics of the AGS are its light weight (17.8 short tons (16.1 t) in its low-velocity airdrop configuration), field-installable modular armor, M35 105 mm caliber soft recoil rifled gun, 21-round magazined autoloader, and slide-out powerpack.

Though it had authorized the start of production of the type classified M8 a year earlier, the Army canceled the AGS program in 1996 due to the service's budgetary constraints.

The U.S. Army recognized the poor performance of the M551 Sheridan light tank in the Vietnam War and began the process of retiring the vehicle in 1977.

Instead of wheeled, it would be a tracked, lightweight, highly agile kinetic energy gun capable of killing enemy tanks and shielded by sufficient armor to protection the crew from artillery and small caliber weapons.

[34] In 1985, Army Vice Chief of Staff General Maxwell R. Thurman approved an amended requirement operational capability (ROC) for the AGS.

[36] 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.

[40][nb 7] In March 1990, Vuono told the Senate Appropriations Defense Subcommittee that the Army was surveying options for acquiring about 70 tanks to replace the Sheridan.

[45] An AGS "rodeo" was held in July 1990 at Fort Bragg, North Carolina, with representative systems submitted from prospective contractors.

[48] The AGS program had gained political favor by this point due in part to the back-to-back successful employment of the Sheridan in two overseas operations.

[49] In October 1990, HASC deferred the Block III main battle tank and directed the Army to make the AGS its top priority modernization program.

[54][55][56] In November 1990, Congressional appropriators sought for the Army to utilize the Marine Corps's developmental LAV-105 for the AGS role or "show clear and convincing evidence that the LAV-105 is unable to fulfill the requirement".

[59] 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.

[63] 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.

[76] In a December 1993 report, the Defense Department Inspector General (IG) cautioned that the AGS would be too heavy for low-velocity airdrop (LVAD).

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.

"[97] The House appropriations national security subcommittee requested that the DoD pause the cancelation of the AGS pending a Congressional review.

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.

[95] 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.

[104] The Army also considered the MGM-166 LOSAT missile, now mounted on a Humvee rather than the originally planned AGS, as another platform offering similar capabilities for the 82nd Airborne.

[98] 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.

The engineering and manufacturing development contract was awarded to FMC in June 1992 for a ballistic structure, six test vehicles, and technical data.

[71] 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.

[111] United Defense provided three AGSs oufitted with levels I, II and III armor for a platform performance demonstration from December 1999 to January 2000.

[112] 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.

[116] 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.

[118] While this decision was on hold, Congressman Robin Hayes expressed frustration that the AGS had not been fielded, and called on the DoD to act swiftly to resolve the delay.

[119] 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.

[125][127] In February 2022, BAE was eliminated from the competition due to noncompliance issues, leaving the General Dynamics Griffin as the only remaining MPF entry.

NBC-sealing of the turret is not possible in any event as the vehicle is exposed to outside air when spent shell cases are ejected and when the main gun is fired in maximum depression.

As of 2019, BAE was working on adding medium-wave infrared sensors and a slew-to-cue system that points the turret in the direction of the incoming missile.