The first objective was achieved by the start of mass production of the mainstay "RGM - 79 Jim", the development of the mobile suits, which is a key element of the Earth Federation 's counterattack in the one - year war. However, because the fighting power in middle range battle was uneasy only with "RGM - 79 Jim" mainly based on "RX - 78 - 2 Gundam", the upper part of the Earth Forces' RX-77-2 Gun Cannon "mass production. However, even with the Earth Federation Army with great industrial power, it was difficult to newly create a mass production line of the RX-77 series under wartime, so we shared parts with "RGM-79 Jim", which is produced as the main machine It was decided to undertake the development of middle-range support type mobile suits.
As development progresses and the prototype rebuilt of "RGM - 79 Jim" is completed, as a result of the test, it is likely that the weight balance collapses greatly when equipped with two cannon guns on both shoulders like the RX - 77 series Turn out. Therefore, based on the data obtained from the test, the balance is adjusted by replacing the Cannon cannon with a single rocket gun with less recoil and the legs with heavy armor specifications close to the RX - 77 series, respectively. The RGC-80 Jim Cannon, a formal adoption machine that gained the performance required by the upper army, was completed.
"RGC - 80 Jim Cannon" improved maintenance performance and mass production performance by making about 60% of the main structure and exterior parts, etc. shared as "RGM - 79 Jim", but the timing of starting mass production is delayed The number of production is small because it has gone. In the ground warfare of the one year war, it was first introduced with the full-scale mass production "RGM - 79 Jim" at the California base recapture operation of the North American front which was a battleground. After that, many aircraft were introduced to the African front where contravention operations continued, as well as Australian front, Jabro defense etc. confirmed. The basic color is a color scheme with a white red similar to Jim plus dark gray, but various colors such as gray and sand color were applied to each battlefield according to the battle area and deployed on each front.
Also, along with the start of "Strategy No. 1 Operation", which is one of the big counter attack strategies in space, it was deployed to the Rebel fleet and Team Fleet and also participated in the Solomon strategy game. Many aircraft have been lost with the Rebel fleet due to the attack of Solar Rey, but it is witnessed that some surviving aircraft are participating in the battle with A · Baaa Ku.
Even after the one year war, the cockpit part has been operated under modernization refurbishment such as changing to the linear seat type, and the aircraft deployed for the defense of Jaburo is confirmed at the time of the Grips war.