The M202 XP Machine Gun is a form of machine gun used in automated stationary gun turrets. They were obsolete as of 2541, and used only in the training of the Spartan-IIIs. They can be loaded with Stun Rounds for training and can fire bullets if needed.
The automated stationary gun used in the training of Spartan-IIIs has a minimum angle of fire; a person can stay out of the cone of fire to avoid getting shot. Their tracking speed is limited, as the Spartan-III's were able to stay well ahead of its line of fire. They are secured to a platform by securing bolts. On the platform, the gun is hooked up by wires to: a radar array that uses radar to target, a power supply that powers the turret, and an automated fire control. They can also be disassembled and be used manually, like a normal gun. For example, this was done in the Spartan-III's training to combat the trainers with more than just their bare hands.
The UNSC also had M202s mounted in automated base defense turrets during 2531. The platforms had up to four M202XP MGs mounted, and they were more sophisticated than those used in the training of Spartan-IIIs, allowing for a larger field of fire.