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
- Dual head-mounted, 60mm caliber, triple-barreled gatling cannons. Each gun is loaded with 400 rounds of ammunition and fires at a rate of 1600 rounds per minute. Primarily used to ward off advancing enemies, shoot down missiles or other lightly armored targets.
- 360mm Cannon
- A pair of 360mm Cannon 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 Beam Spray Gun is essentially a beam rifle in a smaller, weaker form. It has a smaller focusing coil which results in a less powerful, and a more scattered shot. As a result of this, the beam spray gun is less effective at long range, but is better at close range due to a more spread out shot, similar to a shotgun effect. While the beam spray gun is less powerful than the beam rifle, it has been shown to be able to penetrate the armor of a Rick Dom - one of the most heavily armored mobile suits of the One Year War.
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.