The RGM-79SC GM Sniper Custom is a variant of the mass production RGM-79 GM and was first featured in the original design series Mobile Suit Variations (MSV).
Unsatisfied with the performance of the RGM-79 GM, a number of Federation ace pilots requested an improved version of the mobile suit. As a result, two modified GM variants were produced: the RGM-79L GM Light Armor and the GM Sniper Custom. Despite its name, the GM Sniper Custom was a general-purpose unit capable of long-range sniping, medium-range support, and close-range combat.
Compared to the base GM, the GM sniper Custom featured more powerful thrusters on its backpack, which rivalled the RX-77-2 Guncannon in terms of output; additional high-output thrusters on the back of the leg; a pair of powerful cooling units were mounted on the waist armor, allowing stable operation in situations that would otherwise be overtaxing; and an additional armored visor, equipped with an original image sensor and dedicated enhancer, was fitted on its head. Although this visor was meant only for protecting the dual camera eyes during close range combat, it could exhibit extremely high precision when used with the R-4 Type Beam Rifle.