The RGM-79 GM was a mass-produced mobile suit based on the RX-78-2 Gundam. Its basic frame was easily adaptable to modifications into mission-specific GM models, and had a fairly high level of mobility for the time, both on Earth and in space. It had a maximum acceleration of 0.94 G in space, which was better than the Zaku and even the Gundam. On Earth's surface, the GM was also faster than the Zaku II. The armor of the GM was made from Titanium Alloy, a sturdy metal that could be refined more quickly and easily than the Gundam's Luna Titanium Alloy. Although Titanium Alloy is less durable than Luna Titanium Alloy, it is slightly lighter, which reduced the GM's overall mass compared to the Gundam's while still being superior to the Zaku II's super-high tensile steel armor.
The GM was primarily armed with a beam spray gun, a less powerful version of the Gundam's beam rifle that could still destroy mobile suits in a single shot. Early in production, the beam spray gun had yet to be mass-produced so most GMs were equipped with various machine guns. These machine guns continued to be used by the GMs later, and the machine could also use the Gundam's beam rifle when required. It could also use a mass production version of the Gundam's Hyper Bazooka for heavier firepower. For close combat, the GM was armed with a beam saber and a shield similar to those used by the Gundam. Commander units sometimes featured a second beam saber. Lastly, the GM had a pair of head-mounted 60mm vulcan guns for intercepting missiles or stopping enemy units from closing in.