The M203 grenade launcher is an underbarrel weapon featured in Medal of Honor.
Medal of Honor (2010)
The M203 is only available for the last mission and is mounted on Spc. Dante Adams' M4. It does a medium amount of damage, but its blast radius is not very large, and the angle of the grenade can be hard to determine.
The M203 is automatically equipped on the M16 Assault Rifle. It fires a 40mm explosive grenade but its blast radius is not particularly large. It only has two grenades, compared to the other grenade launchers, which have three grenades.