After completing development on the RX-78-01［FSD］Gundam FSD, two projects were undertaken by the Earth Federation Forces . One was the full mass-production of RX-numbered machines, the other was the expanded weapon system FSWS（Full-armour System and Weapon System）plan. The FSWS plan was to strengthen the RX-78 by increasing armor and weapons, and several fuselage design proposals were considered.The FA-78-1 Full Armor Gundam type was outfitted with external armor and weapons upon the fuselage, while the FA-78-2 Heavy Gundam itself was a heavy duty armor fuselage. It achieved improvements in armor, firepower, and maneuverability.
A combat armament that emits a blade-shaped beam which can instantaneously cut through the armor of a mobile suit. One is stored on the left side of the Heavy Gundam's backpack.
Mounted on the right side of the Heavy Gundam's backpack.
Specialized Beam Rifle
The Heavy Gundam participated in the battle of Solomon. It fought Vasily Bosch's Act Zaku during the battle of A Baoa Qu, ultimately immobilizing it. However, it also sustained critical damage during the battle, and was immobilized. Before it could finish off the Act Zaku with its beam cannon, Vasily's teammate interrupted him and rescued Vasily. The Heavy Gundam was apparently consumed by the explosion of the Dolos and destroyed.
Mobile Suit Gundam Origin: Mechanical Archives Vol.30