The standard-issue sidearm for GUN soldiers in the game is the Heckler & Koch USP Tactical. When Shadow is confronted by the GUN Commander in a cutscene, the Commander attempts to shoot Shadow with his USP Tactical, but misses. The gun has a 10-round capacity in-game, and fires semi-automatically.
In some pre-rendered cutscenes, GUN soldiers use M1911A1 pistols. A silhouette of an M1911A1 also appears on GUN supply crates. Shadow is seen holding an M1911A1 in promotional iamges and the opening sequence, but he never uses one in game.
GUN soldiers also use the Heckler & Koch MP5A3 with the Navy trigger group. The gun is fully automatic with a 20-round capacity while used by Shadow. The opening title sequence of the game shows Shadow a much more detailed and accurate MP5; interestingly, the weapon is charged by pumping it as if it were pump-action, though Shadow's hands are so big that he has his fingers in a position to operate the charging handle by doing this.
Error creating thumbnail: File missingHeckler & Koch MP5A3 9x19mm with Navy trigger groupThe MP5A3's in-game model. The weapon lacks a trigger and trigger guard in-game and appears to have a railed handguard which the developers might have mistaken for a pump-action charging handle. Note that the fire selector is on semi-auto, despite being automatic in-game.Error creating thumbnail: File missingShadow carrying an MP5A3 in-game.Error creating thumbnail: File missingShadow loads a magazine into his MP5A3 in the opening sequence.Error creating thumbnail: File missingShortly afterwards, Shadow pumps his MP5A3.
SIG SG 551
The standard assault rifle used by GUN soldiers is the SIG SG 551. When picked up by Shadow, it has a 30-round capacity.
A heavy machine gun that appears to be loosely based on a Browning M1919 appears in the game. It is mounted on turrets which can be used as a stationary weapon (with unlimited ammo) or destroyed and used as a handheld weapon with a 30 round box magazine (somehow a stock and pistol grip appear on the gun when it is destroyed). The weapon also appears in the hands of GUN combat robots and in crates later on in the game. Oddly, it can be fired faster in short bursts than in full-auto.
The various walker mechs used by GUN are armed with missile launchers and GE M134 Miniguns. When these mechs are destroyed, the miniguns can be picked up and used as a man-portable weapon. They are arguably the game's best weapons due to their 40-round magazines, high damage, and fast rate of fire, but they are somewhat usurped by their relative sparsity.
The "RPG" is a fictious weapon with elements from several missile launcers, such as an AT4, an FIM-92 Stinger, an FIM-43 Redeye, a Mk 153 SMAW and an M20 "Super Bazooka." The weapon can fire six homing missiles.
