The M203 40mm Grenade Launcher is used while attached to an M16A2 5.56mm rifle. It is a lightweight, compact, breech loading, pump action, single shot launcher. The launcher consists of a hand guard and sight assembly with an adjustable metallic folding, short-range blade sight assembly, and an aluminum receiver assembly which houses the barrel latch, barrel stop and firing mechanism. The launcher is capable of firing a variety of low velocity 40mm ammunition.

The launcher also has a quadrant sight which may be attached to the M16A2 carrying handle and is used when precision is required out to the maximum effective range of the weapon.

Background: The M203 was designed and procured as the replacement for the M79 grenade launcher of the Vietnam era.