Technology & Combat Characteristics
When the Earth Federation Forces finally began mass-producing the RGM-79 GM in the final months of the One Year War, it was decided that a mid-range fire support unit is needed to aid the GM units. Rather than waste time designing a new mobile suit from scratch, and then straining their resources on new production lines to build this new unit, the Federation Forces simply decided to produce a variant of the standard GM to fill the void.
The Federation's initial attempt was the RGC-80 Prototype GM Cannon. The Prototype GM Cannon was little more than a normal GM with a RX-77-2 Guncannon's head and dual 360mm shoulder-mounted cannons. However there was a critical flaw in this design - the shoulder cannons were too heavy for the light frame of the GM, and the suit suffered from severe recoil and balance issues when the cannons were fired.
- 60mm Vulcan Gun
- These shell firing weapons have high-rate of fire but little power, and can't damage the thick armor of a mobile suit, though it can damage lightly armored areas such as the sensors. They are ideal for shooting down small, lightly armored targets such as missiles, small attack vehicles, etc.
- 360mm Cannon
- A pair of 360mm cannons are mounted on the shoulders, and fed by an internal magazine located inside the main body of the Prototype GM Cannon. While presumably having more power and longer range compared to the Guncannon's 240mm cannons, they are also heavier and this caused the Prototype GM Cannon to suffer from severe recoil and balance issues when firing them.
- Beam Spray Gun
- A handheld mega-particle gun with a lower focusing rate than a beam rifle and short range. The beam spray gun features three different firing modes: a basic single shot mode, a burst shot mode for area suppression, and a range shot mode that scatters the beam to cause damage over a wide area. Output 1.4 MW.
The Prototype GM Cannon 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.