Technology & Combat Characteristics
The RX-77 Guncannon's overall performance as a medium-range support machine was excellent and plans were made to put it into mass production. However, in line with the core of the RX Project, which is to create a multipurpose, easily convertible mobile suit, the design of the Guncannon needed to be simplified. The Earth Federation Forces' plan was to retain the Core Block function of the Core Fighter, with the mobile suit's upper body equipped with cannons for medium-range support. The first Prototype GM Cannon created under this plan was rolled out in Jaburo in October of U.C. 0079.
Equipped with 360mm cannons on both shoulders, the Prototype GM Cannon also combined parts of the RX-77-2 Guncannon, such as its head and forearms, with the body of RGM-79 GM. During tests, it was discovered that the mobile suits had issues with weight balance and stability when firing its cannons. In order to realize shooting performance comparable to the Guncannon, improvements centered on the 360mm Cannons were made. An improved machine called "Type 2" was made around 5 days later, it featured improvements such as attaching additional armor for posture stability to the legs, and several problems were resolved.
- 60mm Vulcan Gun
- A pair of shell-firing armament built into the head. Low offensive power, only used to restrict enemy movement, and lay down a wall of suppressive fire due to their rapid fire capability.
- 360mm Cannon
- A pair of rocket cannons mounted on the shoulders. Although it is a low-recoil type, there were problems with weight balance and stability when firing, and improvements were made in Type 2.
This machine was deemed insufficient, and the Federation's researchers and engineers went back to rework the design, producing the RGC-80 GM Cannon as their final product.