For years, American troops have been complaining about the inadequate sight on the Mk 19 40mm automatic grenade launcher. The brass finally paid attention, and then some. Last year, a new, and very effective mechanical sight was introduced. But the army call for a new Mk19 sight also attracted some even more ambitious efforts. And one of them has resulted in a remarkable electronic sight. Combining a GPS, laser rangefinder and computer, the new Mk19 FCS (Fire Control System) enables gunners to put the first round on the target, at extreme ranges (over 2,000 meters). The FCS can also fire an accurate pattern of 40mm grenades at those same ranges. Moreover, the GPS enables a FCS equipped Mk19 to accurately fire on a target the gunner can't see. The FCS also has a camera, which can mark targets, out to 5,000 meters, on a photo, which can be then transmitted to other troops or headquarters. The FCS is also very easy to use for anyone with Mk19 experience. You laze the target, and then use the aiming dot in the sight to mark where the rounds will go.
Getting the first rounds on the target is very important, because once those 40mm rounds start going off, the enemy will dive for cover. With the older sights, the first round was a guess by the gunner, and usually close, but not on the target. Subsequent rounds were on target, but by then many of the enemy troops were behind cover.
The FSC is but one of many improvements. But Mk19 gunners love the new sight, and the word has quickly gotten around. So the army has a problem getting FCS, which is still in development, to all the troops who are now demanding it.
In the meantime, Mk19 gunners will have to be content with other recent improvements. Last year, a new rear sight for the Mk19 became available. The Mk19 has been around for a long time, without much change. The iron rear sight was designed for older ammo, which caused the sight to be inaccurate. So users were more often just "walking in" exploding rounds to the target. That's because the old sight was not only inaccurate, but was always a hassle to use. The new mechanical sight solved most of the problems, and is cheaper (partly because it uses 27 fewer parts) and easier to maintain.
Meanwhile, the U.S. is considering replacing its 1960s era Mk19 40mm grenade launchers with a lighter and more effective Mk47 model. The replacement weapon is being tested in combat, while the army is still ordering new Mk19s. This is because the Mk19 gets the job done, is cheaper and the troops like it. Moreover, a new recoil system is ready for the Mk19 as well, which keeps the weapon steadier when firing. That also helps accuracy.
The Mk47 is lighter (18.2 kg/40 pounds) than the 35 kg (77 pound) Mk19. It is a little more compact, and has the electronic sighting and arming system which enables the gunner to determine the distance of the target (with a laser range finder), then push a button to have the weapon electronically program each shell, just before it is fired, for the number of seconds until the shell will explode, at the proper range from the gun, and above the enemy troops. If the time fuze does not work, the shell explodes when it hits something. The Mk47 can also operate like the Mk19, using "dumb" ammo that lacks the time fuze. This is what the new FCS does for the Mk19.
Both these 40mm weapons have a max range of 2,000 meters (and an effective range of about 1,500 meters). The Mk19 weapon, with a tripod, weighs 61.8 kg (136 pounds), while each 48 round magazine weighs 27.3 kg (60 pounds). There is a new, lighter, tripod available, that reduces weight by 13.2 kg (29 pounds) The Mk19 effective rate of fire is about one round per second, and is usually fired in short (a few rounds) bursts of these 542 gram (19 ounce) grenades (which kill or incapacitate most people within six meters of the explosion and can wound at twice that).
The Mk19 is more complex than your usual machine-gun, expensive (about $20,000 each) and jams more frequently (once every thousand rounds, compared to once every 10,000 rounds for the M2 12.7mm machine-gun.). But it is reliable enough to remain popular and in demand. The lighter Mk47 costs about 50 percent more, and is about as reliable as the Mk19.
The U.S. Navy developed the Mk19 in the 1970s, for use on river and coastal patrol boats. The army adopted the weapon in the early 1980s, but it wasn't until the 1991 Gulf War that the Mk19 saw much action. Or at least some action. Users noted that the Mk19 was very effective out in the open, not so much in urban areas. In 2003, when the army and marines encountered much more combat out in the open, they found the Mk19 to be very valuable, more so than machine-guns.