October 14,2008:  In the last year, the U.S. Army has ordered another 6,000 Mk19 automatic grenade launchers. These 40mm weapons have a max range of 2,000 meters (and an effective range of about 1,500 meters). The weapon and tripod weigh 136 pounds, while a magazine with 48 rounds weighs 60 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 19 ounce grenades (which kill or incapacitate most people with 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 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.

While there has been a lot of work on a 25mm replacement for the Mk19, the 40mm weapon is proven and popular. The 25mm M-307, was designed so it could fire either the computer controlled 25mm "smart shell", or (by changing the barrel and receiver), .50 caliber ammo. This may still happen, as the smart shell works well enough that a lightweight (12 pound) weapon, the XM-25 has been developed. This fires the five ounce 25mm shells out to about 700 meters. The Mk19 still has the edge in terms of range and lethality, which apparently explains the recent purchases of new Mk19s, and limited procurement of the XM-25.