Paint pellet gun
From Halopedia, the Halo wiki
Introduction
The Paint Pellet Gun is a UNSC weapon similar to the "paintball" marker pistol of the 21st century. Like its predecessor, it fires small plastoid pellets filled with brighty-colored paint. The paint pellet gun is often used by UNSC forces as a non-lethal way of training new recruits in basic combat tactics, or as a method of testing new equipment in combat situations without permanently damaging it.
Uses
The Paint Pellet Gun was used by CPO Mendez and drill instructors to train the Spartan-II's on the 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.
Sources
Eric Nylund, The Fall of Reach, p. 47.
