Technology & Combat Characteristics
To hunt down the Zeon Remnants, the RX-77-3D Guncannon was refitted with extra firepower. Other improvements included the addition of four more verniers on each leg to increase speed. With these improvements the Guncannon Heavy Arms Type D was more mobile and more heavily armored. The RX-77-3D Guncannon's armament included a shield, head vulcans, grenade rack and a Balzak Type 380mm Rocket Bazooka. It also has two 240mm cannons which only held 20 rounds per cannon, meaning the pilot had to learn how to conserve cannon ammunition and use it wisely. Although it was successful, the RX-77-3D did not see full mass production.
- 60mm Vulcan Gun
- A standard armament of the mobile suits that are descended from the Earth Federation Forces's RX series is a pair of head mounted 60mm vulcan guns. These shell firing weapons have a high-rate of fire but have little power and can't damage the thick armor of a mobile suit, though it can damage lightly armored areas such as the sensors. The weapons are ideal for shooting down small, fast moving, lightly armored targets such as missiles, small land vehicles, and attack helicopters.
- 240mm Cannon
- One mounted over either shoulder, each mid-range fire support artillery cannon is fed by a twenty (20) round internal magazine located inside the main body of the Guncannon. Each 240x800 millimeter shell has a 95 kilogram HE fragmentation warhead, with a casualty radius of 40 meters. Can fire to distances up to 2.5 kilometers.
- BAUVA*XBR-L Beam Rifle
- The Guncannon Heavy Arms Type D can be equipped with a larger and longer-range portable mega particle cannon than the RX-78 GUNDAM. It is powered via an internal energy capacitor with an average charge of fifteen (15) rounds. Each beam is capable of tearing through the medium and heavy armor of enemy MS and MA. Maximum effective range of 2.8 kilometers.
- HWF GMG·MG79-90mm Bullpup Machine Gun
- The bullpup machine gun is an open-bolt, gas-operated, magazine-fed, mobile suit handheld sub-machine gun. It does not require energy to be used, however it is ineffective against heavy armor. When the magazine is empty, it can be discarded and replaced with a new one.
- Balzak Type 380mm Rocket Bazooka
- A clip fed bazooka that fired rocket rounds.
- To counter the weight of the Rocket Bazooka, a heavy shield was installed to balance the suit while jumping.
- "Fire Nut" Grenades
- The Guncannon Heavy Arms Type D is equipped with a set of Fire Nut grenades which are stored inside an open rack on its left waist armor. A compact, powerful bomb which can be hand-thrown by Federation's mobile suits, the Fire Nut can be thrown like regular grenades and set to detonate upon impact with the target. It is powerful enough to destroy an enemy's mobile suit.
As Zeon was losing the One Year War, they eventually had to resort to guerrilla tactics to suit their diminished MS forces. To counter this, the Earth Federation took the RX-77-2 Guncannon, which was one of the most successful MSs of the One Year War, and refitted it to hunt down remaining Zeonic forces. The RX-77-3D was then born. The Guncannon Heavy Arms Type D was first deployed in the late phase of the One Year War used by the Earth Federation Ground Forces on the African front. One unit was also assigned to the penal battalion Slave Wraith, and painted in their team custom colors.