The M203 is a single shot 40 mm grenade launcher designed to attach to a rifle. It uses the same rounds as the older M79 "shotgun"-type grenade launcher, which utilize High-Low Propulsion System to keep recoil forces low. Though versatile, and compatible with many rifle models, the M203 was originally designed for the U.S. M16 and its variant, the M4 Carbine. The launcher can also be mounted onto a C7, a Canadian version of the M16 that uses an optical scope instead of an iron sight, and requires the bottom handguard on the rifle to be removed in order to mount the launcher.
You recive first recive the M203 in the 5th mission mounted on the under-barrel of an m16