Technology & Combat Characteristics
Originally, it was planned for the RX-77-2 Guncannon to be mass-produced with a few tweaks to its design, but in consideration of the wartime situation, the design was changed to make use of the existing production line of the RGM-79 GM. Following a series of trial and error, the GM Cannon was created as a simplified mass production model of the Guncannon. A medium-range support mobile suit, the GM Cannon shares 60% of its parts with the GM, and has a high initial velocity cannon of the same caliber as the Guncannon's attached to its notched right shoulder. Its legs are fitted with removable left and right split type increased armor to maintain the mobile suit's balance when firing the cannon during ground combat.
History
Initially only six RGC-80 GM Cannons were produced and fielded as part of the Earth Federation Forces's campaign to retake the North American continent. By the time the Earth Federation Forces had recaptured California Base from the Principality of Zeon forces on North America's Pacific Coast, the GM Cannons had proven themselves on the field and was approved for mass-production. Additional GM Cannons were constructed and distributed to various Earth Federation Forces battalions around the Earth to assist in driving the Zeon forces back to space.
By the end of the war, 58 GM Cannons were produced in total. 14 units were assigned to the Revil and Tianem fleets, 6 units were assigned to the North American front, 19 units were assigned to Africa, one of which was given to ace pilot Lydo Wolf and painted in his trademark black custom colors, and 9 units were assigned to Jaburo's defense force. In addition, at least three units were assigned to the Australian front and used by the White Dingo Team. The GM Cannon continued to see active service even after the war and into the Gryps War in U.C. 0087.