LEGEND:

Gold: Iron sight
Light green: Scope
Light grey: Zoom control
Dark grey: Zoom slider
Purple-Blue: General-purpose firearm
Light purple: Fingerguard
Dark green: Reinforcement
White: Trigger
Dark brown: Clip holder
Light brown: Grip
Pink: Mode switch
Dark purple: Body seperator
Blue: Grenade launcher
Red: Grenade door

NOTES:

Zoom control/slider: Changes zoom level
Mode switch: Changes modes from Safe, GL (Grenade Launcher), SS (Single Shot), TS (Tri-Shot) and AS (Auto Shot)
Upper body: Changeable to a shotgun or other "General Class" weapon, making SS, TS and AS work as the same mode, and the clip bay replaced with a bay half the size, reaching from the top to middle, then a switch to load a second burst, and then a room for a third, loaded clip in the bay, effectively making the shotgun able to shoot thrice without pumping. The load is automatic.
Name: Half-triangular shape