The Mk 19 is a belt-fed, blowback-operated, air-cooled, crew-served, fully automatic weapon that is designed not to cook off. It fires 40 mm grenades at a cyclic rate of 325 to 375 rounds per minute, giving a practical rate of fire of 60 rounds per minute (rapid) and 40 rounds per minute (sustained). The weapon operates on the blowback principle, w