Technology & Combat Characteristics
When the Earth Federation Forces finally began mass-producing their own RGM-79 GM model of mobile suits in the final months of the One Year War it was decided that there would need to be a mid-range fire support unit to properly supplement their close-range GM forces. Rather than wasting the time designing a new mobile suit, and then putting a strain on resources setting up the new production lines that would be necessary to build them, the Federation Forces decided to simply produce a design variant of the standard GM to fill the void in their ranks.
The first GM redesign created in the attempt to solve the Federation's problem was the RGC-80-1 GM Cannon Test Type. The GM Cannon Test Type 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 first design. The dual shoulder cannons were far too heavy for the light frame of the GM, and when the cannons were fired the unit experienced severe recoil and balance problems.
- 60mm Vulcan Gun
- Dual, head-mounted, triple-barreled gatling cannons in caliber 60 millimeter. Each gun is loaded with 400 rounds of ammunition and fires at a rate of 1600 rounds per minute. Primarily for the elimination of aerial and light armor targets. With sustained fire, the stream of bullets can cause damage to enemy mobile suits.
- 360mm Cannon
- The pair of 240mm Cannon of the Gucannon were replaced by two 360mm cannons mounted on the shoulders, and fed by an internal magazine located inside the main body of the GM Cannon Test Type. While presumably has more power and longer range compare to the 240mm cannons, it is also heavier and the weight of two 360mm cannons causes problems to the GM Cannon Test Type, including severe recoil and imbalance.
- 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 GM Cannon Test Type 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.