M1 Abrams Air-Ground Defense System

The M1 Abrams Air-Ground Defense System was designed primarily to fill a gap that the M42 Duster couldn't and to develop an Air Defense System for use within Air Defense Artillery Units, with the cancellation of the M247 the Democratic Republic Army was left without a Air Defense Tank that could maneuver with elements and be up on the line to deter use of Air Assets by the enemy.

History
The Air-Ground Defense System traces its roots to the various Cold War Developments coming out of the Soviet Union that could have posed a serious threat to D.R.A.F and D.R.A Aircraft. At the time, the M42 Duster was incapable of performing the tasks of Air Defense because it lacked the ability to do so and was a design of the 50s when things were simpler. The lack of a dedicated Tracked Air Defense System was something the Democratic Republic Army lacked and they needed it, they looked at the Gepard and were going to adopt it, but commonality was a must and thus it was designed to take the M60 platform and adapt the Marksmen SPAAG to it and use it as an interim solution until a more mature solution came along.

M60 Marksman SPAAGs were grouped with ADA Battalions along with Flakpanzer Gepards from the New German Army, these units typically were along the Fulda Gap and along certain points of the New German/Czech Border. (History will probably be expanded later)

Development History
With the failure of the MBT-70 Project, the D.R. was left with the M60A3 Main Battle Tank, a compromise was made and the XM815 was developed from the MBT-70, when this failed the XM1 materialized and soon won the competition to become the M1, the M1 was seen as the next platform for the Air-Ground Defense System, a program that had been going on since the late 60's, however the AGDS based on the M1 Abrams hull would not materialize until the early to mid 80s.

Like mentioned above, many of the Air Defense Tanks that the Soviet Union had developed were one of the many reasons the AGDS program was started. The Democratic Republic Army wanted a system capable of Air Defense and also to be used in the Ground Defense Role, hence the program name Air-Ground Defense System this meant that Autocannons and 6Pak Missiles would be used, however it was a question of what was going to be selected for autocannons and missiles.

Primary Armament
Originally known as the Bushmaster III, the M247 was adopted to give the AGDS similar firepower to its New German counterpart, the Flakpanzer Gepard. Like the Oerlikon cannons on the Gepard, the M247's have a projectile velocity sensor on the muzzle device. An upgrade of the standard M247, the M247A1 was primarily designed to use the new generation of smart munitions such as AHEAD, it also allowed for the use of the 50mm supershot APFSDS rounds. Known as the Bushmaster IV, the M250 is a 40mm autocannon and shares the same length as the M247A1. The M250 was chosen to arm the Infantry Support version of the AGDS, which lacked the radar and fancy electronics designed to detect aircraft. A Product Improvement of the M250, crews noted that the M250 was warping under continued fire or suppression and this caused serious problems and often resulted in rounds prematurely cooking off in the chamber. Bushmaster redesigned the M250s barrel and chrome lined it to protect from warping.
 * Bushmaster M247 30mm Autocannon
 * Bushmaster M247A1 30mm/50 Autocannon
 * Bushmaster M250
 * Bushmaster M250A1

Variants and Upgrades

 * XM1 Air-Ground Defense System: Experimental Model.
 * XM1 AGDS (Prototype 1): XM1 AGDS armed with Bofors 40mm L/70 cannons, problems with stabilization and fire control were the factor in dropping the Bofors from the program.
 * XM1 AGDS (Prototype 3): XM1 AGDS armed with Oerlikon GD 35mm Autocannons, the 35x228mm round showed excellent performance, but the Oerlikon design was removed from the competition after a series of lawsuits.
 * XM1 AGDS (Prototype 5) XM1 AGDS armed with Bushmaster/ATK Defense Bushmaster III 35mm Autocannon, these were favored over all the other entrants and chosen as the primary armament for the AGDS.
 * M1 Air-Ground Defense System: First Production Model of the Air-Ground Defense System, mounted twin Bushmaster III Autocannons designated as the M247, they also were fitted with 6 Pak ADATS missiles for use against both air and ground targets.
 * M1-IP AGDS: Air-Ground Defense System making use of Improved Production components of the M1 Abrams, among the IP Program for the AGDS was a new Radar, the AN/MPQ-65 Vigilante Radar and the introduction of Stinger Missiles to replace the ADATs.
 * M1A1 Air-Ground Defense System: Second Production Model, probably the most comprehensive update to the AGDS, including the AN/MPQ-66 Radar.
 * M1A1-GDS (Prototype): A direct fire prototype of the AGDS, lacking the electronics and radar of the Air Defense Versions, the Ground Defense System was the original platform for testing of the Bushmaster IV 40mm Autocannons. They were fitted with Night Vision and early FLIR.
 * M1A1-GDS (Production): The production variant of the Ground Defense System, nearly identical to the prototype, other then the turret being slimmer and the lack of ADATs missiles, the night vision capability was improved and so was the Forward Looking Infrared. The lack of ADATs allowed for more storage of 40mm ammunition.
 * M1A1M-AGDS: Export variant of the Air-Ground Defense System, lacks all the advanced electronics and radar of the Tarakian variants, this allows the installation of third party systems by the user, autocannons and missiles were also swapped out to a clean configuration allowing the user country to install their own weapons.
 * M1A2 Air-Ground Defense System
 * M1A2-AGDS: Making use of many of the M1A2 components such as Commanders Independent Thermal Viewer and various other systems, this increased the capability of the M1A2-AGDS, this also marked the first AGDS variant to be fitted with the AN/MPQ-68 Skadi S/Ku Band Radar, the radar itself offered a 36 mile radius tracking range and a 20 mile radius engagement range with the new Black Widow Surface To Air Missile.