Paint pellet gun
From Halopedia, the Halo wiki
Introduction
The Paint Pellet Gun is a UNSC weapon that fires small pellets filled with paint.
Uses
The Paint Pellet Gun was used by CPO Mendez and drill instructors to train the Spartan-II's on the agricultural planet, Reach. It was used to snipe the Spartans in parade drills to teach them a lesson that things would be twisted, and unpredictable.
Service
It was probably only used in training when they were young, 6, 7, 8, 9 years old.
Speculation
It was only mentioned in one place, but it's highly possible that Mendez used them in other lessons and missions.
Sources
Eric Nylund, The Fall of Reach, p. 47.
