The Mk 19 Grenade Launcher is a belt-fed automatic 40 mm grenade launcher or grenade machine gun that entered U.S. military service during the Cold War, first seeing action during the Vietnam War and remaining in service today.
The Mk 19 fires 40 mm grenades at a cyclic rate of 375 to 400 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, which uses the chamber pressure from each fired round to load and re-cock the weapon. The Mk 19 is able to lob its grenade at a maximum distance of 2,212 meters, though its effective range for a point target is about 1,500 meters, since the large rear leaf sight is only graduated to 1500 meters. The nearest safe distance to launch the grenade is 75 meters. In addition, the Mk 19's flash suppressor and its lack of smoke during firing makes it difficult for enemies to spot and counter it. For night operation, an AN/TVS-5 night vision sight can be fitted.
The Mk 19 is a man-portable crew-served weapon that can fire from a tripod mounted position or from a vehicle mount (this being the preferred method as the weapon alone weighs 75.6 lbs). The primary ammunition for Mk 19 is the high explosive dual-purpose M430 grenade. Upon impact, the grenade can kill anyone within the radius of five meters, and wound them within the radius of 15 meters. It can also punch through two inches of rolled homogeneous armour with a direct hit (0 Degree Obliquity), which means it can penetrate most infantry fighting vehicles and armored personnel carriers. It is especially effective when used against enemy infantry formations. The ammunition comes in 32 or 48 round cans weighing 42 and 60 lb (20 and 30 kg). Due to its low recoil and comparatively light weight, it has been adapted for use on many different platforms, including small attack boats, fast attack vehicles such as the Humvee (HMMWV), AAV and Stryker, military jeeps and a large variety of naval mounts.
The Mk 19 automatic grenade launcher replaced the earlier Mk 18 hand-cranked multiple grenade launcher. The 40 mm ammunition used (40x53mm) is not interchangeable with that used in the M203 (40x46mm). The M203 grenades are technically "low-velocity" grenades, and are generally of the standard High Explosive variety, whereas the Mk 19 utilizes "medium-velocity" High Explosive Dual-Purpose (HEDP) variety. The Mk 19 utilizes an open bolt principle. The rounds are mechanically fed onto the bolt face with the pull of the charging handles. When the trigger is pressed, the bolt closes, and the firing pin is released. The recoil blows back the bolt, dropping the empty casing, and then feeds a new round onto the bolt face. This design has caused sporadic fatalities in the crews that operate the system. If the weapon system jams, the operator many times must remove a live round from the open bolt face. If the breech closes during this procedure, the round can detonate inside the gun, killing and/or maiming anyone nearby. However, the weapon will not accidentally or intentionally fire a round if one of the charging handles is in the down position. These incidents are rare.
The Mk 19 is made by General Dynamics and Saco Defense Industries.
It was originally fielded by the US Navy in Vietnam for river patrol boats, but was adopted and improved upon by the US Army. The Israeli Defence Forces also adopted the weapon, fielding it in infantry and mechanized units. Sweden made the Mk 19 under license as the Grksp 40 mm grenade launcher. Taiwan has this made under license as the Type 83 made by the Combined Service Forces.
The Mk 19 has been used by American forces in Somalia (1993) and in Iraq (1991) by special forces operating behind enemy lines. It is currently in widespread use in the U.S. Military