The RX-77 Guncannon is an excellent medium-range support mobile suit and plans were made to put it into mass production. However, in line with the core of the RX Project, which is to create a multipurpose, easily convertible mobile suit, the design of the Guncannon needed to be simplified. The Earth Federation Forces' plan was to retain the Core Block function of the Core Fighter, with the mobile suit's upper body equipped with cannons for medium-range support. The first Prototype GM Cannon created under this plan was equipped with two shoulder-mounted 360mm cannons, and combined several parts of the Guncannon, such as its head and forearms, with the body of a RGM-79 GM. An improved machine called "Type 2" was later made, featuring modified cannons for better shooting performance and additional armor on the legs to improve posture stability.
GM Cannon Test Type
（RGC-80-1）The RX-77 Guncannon is an excellent medium-range support mobile suit and plans were made to put it into mass production. However, in line with the core of the RX Project, which is to create a multipurpose, easily convertible mobile suit, the design of the Guncannon needed to be simplified. The Earth Federation Forces' plan was to retain the Core Block function of the Core Fighter, with the mobile suit's upper body equipped with cannons for medium-range support. The first Prototype GM Cannon created under this plan was equipped with two shoulder-mounted 360mm cannons, and combined several parts of the Guncannon, such as its head and forearms, with the body of a RGM-79 GM. An improved machine called "Type 2" was later made, featuring modified cannons for better shooting performance and additional armor on the legs to improve posture stability.