A Prototype Artillery Mobile Suit

The GAT-X103 Buster Gundam is a prototype artillery mobile suit piloted by Dearka Elsman.

One of the five mobile suits developed as part of the Earth Alliance's G Project, the Buster Gundam is an artillery mobile suit and adopts the X100-series frame, similar to the one used by the GAT-X102 Duel Gundam. It has firepower rivaling that of a battleship's and is meant to provide rear support for the other units and to attack enemy ships or facilities from a distance. Due to its role, the main sensor camera on Buster's head is very important and is protected with additional armor. 

 Its primary armaments are the gun launcher and high-energy rifle, both are energy intensive and have their own sub-generators. They can also combine to form the more powerful anti-armor shotgun or the hyper impulse long-range sniper rifle, with the improved firepower seemingly caused by the linkage of the sub-generators. Although the suit has no close combat weapon, it has a pair of shoulder-mounted missile pods that can be used to discourage enemy units from closing in. Like other units in the G Project, Buster has Phase Shift armor, making it nearly impervious to physical weapons.

Armaments 

220mm 6-tube Missile Pod 

Mounted on both shoulders, they compensate for the Buster's poor close combat capability, allowing it to fire a rain of missiles to destroy enemy units or to stop them from moving closer. They can also be used for bombing bases, anti-ship attacks, and missile interception. 

350mm Gun Launcher

 Attached to the right side of the waist and carried in Buster's right hand when in use. It is a projectile weapon akin to a railgun or linear gun, which uses electromagnetic forces rather than gunpowder to launch its projectiles. In addition to ordinary solid shells, the gun-launcher can also fire specialized munitions such as armor-piercing and high explosive rounds. 

Anti-Armor Shotgun 

When the High-energy Rifle and Gun Launcher combine, with the Gun Launcher on the front, it forms a very powerful shell-firing Anti-Armor Shotgun. It fires a single stream containing multiple shells that later splits apart, resulting in a scatter shot that damages a wide area. It appears that about four or five shells fired from the Anti-Armor Shotgun is enough to destroy some battleships. Although the combined form has higher power, the rate of fire is decreased. 

94mm High-energy Rifle 

Attached to the left side of the waist and carried in Buster's left hand when in use. It is a beam weapon similar to the beam rifle, and is the highest caliber energy rifle among those used by other units in the G Project. Its destructive power is above a battleship's beam cannon despite its smaller size. 

Hyper Impulse Long-Range Sniper Rifle 

When the High-energy Rifle and Gun Launcher combine, with the High-energy Rifle on the front, it can form a Long-Range Sniper Rifle. This beam cannon type weapon has a higher energy output, firing a larger beam capable of penetrating several targets, including battleships. As the name implies, it also features sniping capabilities due to the longer range of the beam. Although the combined form has higher power, the rate of fire is decreased.

 Special Equipment & Features 

Phase Shift Armor 

As with all of the G Project mobile suits, the Buster Gundam is equipped with phase shift armor. When activated the Buster's color is changed from a light grey to a beige scheme with a bit of green and orange mixed in. Phase Shift armor, when activated, renders the Buster immune to physical attacks such as bullets, the GINN sword, or against missiles. However Phase Shift armor continually drains the battery of energy, shortening the mobile suit's combat endurance, and uses up additional energy when it is hit. 

Operating System 

The Buster uses the General Unilateral Neuro-Link Dispersive Autonomic Maneuver Synthesis System.

History

Battle of Heliopolis 

The Buster Gundam was one of the prototype mobile suits created by the Earth Alliance under its G Project during the First Alliance-PLANT War. Together with four other machines, the GAT-X102 Duel Gundam, GAT-X105 Strike Gundam, GAT-X207 Blitz Gundam, and GAT-X303 Aegis Gundam, the Buster was secretly manufactured at the Orb Union's space colony Heliopolis. The Buster was later stolen by ZAFT's Le Creuset Team on January 25, CE 71, alongside the Duel, Blitz, and Aegis.

 Following the Archangel to Earth Piloted by Dearka Elsman, the Buster was deployed with the other stolen Gundams against the Strike Gundam and the Alliance's new battleship, the Archangel, several times in space. During these battles, the Buster was usually partnered with the Blitz to engage the enemy ship. Despite their failure to destroy the Strike and the Archangel, the Le Creuset Team was able to heavily damage the previously impregnable Artemis during the Battle of Artemis, and then decimate the Alliance's 8th Fleet in the Battle of Orbit. In this latter battle, Dearka overextended during his attempt to stop the Archangel's descent to Earth, causing the Buster to be caught in the Earth's gravity well. 

Battle of Talbadiya

 The Buster survived the atmospheric entry with the Duel, and they were later assigned to Andrew Waltfeld's North Africa team for the battle against the Archangel and the Desert Dawn. The two Gundams were deployed atop the Lesseps in the battle against the Archangel, as they could not keep up with the TMF/A-802 BuCUEs. The Buster eventually left its position when the beams fired by the Archangel destroyed where it was standing atop the Lesseps. Landing on the desert, the Buster had difficulties walking as it was not properly adjusted to the sandy terrain. 

 Zala Team 

Following the defeat of Andrew Waltfeld's forces, the Buster and Duel met up with the Blitz and Aegis that arrived on Earth, and they operated from a Vosgulov-class submarine. The group made two separate failed attacks on the Archangel, with the former, the Third Equatorial Skirmish, ending due to the battle encroaching on Orb Union's waters, and the latter, the Battle near Orb, resulting in the destruction of the Blitz and death of its pilot, Nicol Amalfi. An angered Dearka then worked with his remaining teammates to avenge Nicol, attacking the Archangel once more at the Battle of the Marshall Islands. During the fight, the Buster fought the FX-550 Skygrasper piloted by Mu La Flaga, and they were evenly matched. While the Duel was later disabled by the GAT-X105+AQM/E-X01 Aile Strike Gundam and the Aegis took its place, the Buster got in close and attempted to sink the Archangel, but was stopped by Mu's Skygrasper. The Buster and Skygrasper then traded shots, with the mobile suit clipping the support craft's right wing, but losing its left arm to the support craft's attack, before crash landing. Damage from the fall immobilized the Buster, forcing Dearka to surrender when the Archangel aimed its weapons at his mobile suit.