The M203 grenade launcher uses several fixed-type, low-velocity 40-mm rounds. The M203 fires high-explosive, illuminating, signaling, CS, and training ammunition. All M203 grenade launcher rounds are fixed rounds.The MK19 40mm Machine Gun fires six types of cartridges:
- M381 HE
- M386 HE
- M397 Airburst
- M397A1 Airburst
- M406 High-explosive (HE)
- M433 High-explosive dual purpose (HEDP)
- M441 HE
- M576 Buckshot
- M583A1 40MM WS PARA ILLUM
- M585 White star cluster
- M651 CS
- M661 Green star cluster
- M662 Red star cluster
- M676 Yellow smoke canopy
- M680 White smoke canopy
- M682 Red smoke canopy
- M713 Ground marker - Red
- M715 Ground marker - Green
- M716 Ground marker - Yellow
- M781 Practice
- M918 Target Practice
- M992 Infrared Illuminant Cartridge (IRIC)
- 40MM NON-LETHAL ROUND
- 40MM CANISTER ROUND
- 40mm Sponge Grenade
