Technology & Combat Characteristics
Although the RX-77-3 Guncannon Heavy Arms Type is an improvement over the RX-77-2 Guncannon, with lower recoil when firing the cannons and better weapon as well as armor capabilities, its mobility still leave much to be desired. To address this issue, one of the Guncannon Heavy Arms Type was improved into the RX-77-3D Guncannon Heavy Arms Type D upon orders from the Earth Federation Forces. The Guncannon Heavy Arms Type D has additional vernier thrusters on its backpack and legs to improve mobility. It also has additional armor on its head and shoulders. Thanks to the four new leg thrusters, the increase in weight caused by these added armor do not affect the suit's mobility. Interestingly, the Guncannon Heavy Arms Type D reverts to the knee armor of the original Guncannon.
With its enhanced mobility, the Guncannon Heavy Arms Type D’s combat range also widen. Thus, although a mid-range support unit, it can also function as a general-purpose unit with performance close to that of a melee combat machine. Armament wise, it has similar weapons as the original Guncannon and Guncannon Heavy Arms Type. After the first Guncannon Heavy Arms Type D unit displayed high performance during tests, the suit was formally adopted by the Earth Federation Forces. However, due to its high cost and the completion of the superior RX-77-4 Guncannon II soon after, the Guncannon Heavy Arms Type D was produced only in limited numbers.
- 60mm Vulcan Gun
- A standard armament of many Earth Federation Forces's mobile suits is a pair of head mounted 60mm vulcan guns. These shell firing weapons have a high-rate of fire but little power and can't damage the thick armor of a mobile suit, though they can damage lightly armored areas such as the sensors. They are ideal for shooting down small, lightly armored targets such as missiles, small vehicles, etc.
- 240mm Cannon
- A pair of shoulder-mounted 240mm cannons served as the Guncannon Heavy Arms Type D's main weapon. Like the ones used by the Guncannon Heavy Arms Type, the Guncannon Heavy Arms Type D's cannons have a higher rate of fire, better ammunition feed system and cause less recoil when fired than those of the RX-77-2 Guncannon.
- BAUVA*XBR-L Beam Rifle
- The Guncannon Heavy Arms Type D can be equipped with the same beam rifle as the RX-77-2 Guncannon. It is powered via an internal energy capacitor with an average charge of 15 rounds. Each beam is capable of tearing through the armor of enemy MS and MA. Maximum effective range of 2.8km.
- Balzak Type 380mm Rocket Bazooka
- An optional MS-use Bazooka developed for the GM Series, it is also often used by the RX-77 series. Besides having enhanced accuracy due to the sensor mounted on top of the weapon, it is also lightweight, easy to use and has high shooting performance.
- RGM*S-Sh-WF/S-00109 Shield
- Mounted on the forearm, this is the same defensive armament as used by the Gundam Ground Types and GM Ground Types. However, the primary purpose for the Guncannon Heavy Arms Type D to equip this shield is to help maintain its balance while jumping whenever it carries large weaponry, such as the Balzak Type 380mm Rocket Bazooka.
- Hand Grenade
- The Guncannon Heavy Arms Type D has an unknown number of hand grenades stored in a rack on its left side armor. Various types of hand grenades can be stored, including one known as 'Cracker', which breaks up into several smaller explosives in midair, and is also used by Zeon's mobile suit.
The Guncannon Heavy Arms Type D was first deployed in the late stages of the One Year War, and 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.