After over a decade of development, the revolutionary, and very high-tech, XM-25 grenade launcher is undergoing final tests, prior to mass production, and distribution to the troops. It was four years ago that six XM-25s were delivered to the U.S. Army for troop testing. While the troops have been very enthusiastic about the new weapon, there were a lot of suggestions, mostly about minor items. So the army kept tweaking and refining the weapon.
The XM-25 was originally one of two weapons (the other being a 5.56mm rifle) incorporated in the 18 pound XM-29 OICW. The OICW was originally developed as a replacement for the 40mm grenade launcher, with the intention of giving the grenadier some rifle firepower as well. Didn't work out as intended.
The 40mm rounds weigh 19 ounces each, the original 20mm OICW round weighed half that. This was one of the several major problems with the OICW. It was too heavy and ungainly, and the 20mm "smart shell" it fired did not appear capable of effectively putting enemy troops out of action, especially compared to the 40mm shell it was replacing. So, in August, 2003, it was decided to take the 5.56mm portion of the OICW and develop it as a separate weapon (the XM-8) and develop the grenade launcher part that fired the "smart shell" as the XM-25. But the XM-25 would use a 25mm shell, which would generate 50 percent more fragments (and heavier ones at that) than the 20mm shell of the OICW.
The 20mm and 25mm "smart shells" both use a computer controlled fuze. The XM-25 operator can choose one of four different firing modes via a selector switch on the weapon. The four modes include "Bursting" (airburst). For this to work, the soldier first finds the target via the weapons sighting system. The sight includes a laser range finder and the ability to select and adjust the range shown in the sight picture. For an air burst, the soldier aims at an enemy position and fires a round. The shell is optimized to spray incapacitating (wounding or killing) fragments in a roughly six meter (19 foot) radius from the exploding round. Thus if enemy troops are seen moving near trees or buildings at a long distance (over 500 meters), the weapon has a good chance of getting them with one shot. M-16s are not very accurate at that range, and the enemy troops will dive for cover as soon as M-16 bullets hit around them. With smart shells, you get one (or a few) accurate shots and the element of surprise.
The other modes are "PD" (point detonation, where the round explodes on contact), PDD (point detonation delay, where the round detonates immediately after it has gone through a door, window or thin wall) and "Window", which is used for firing at enemy troops in a trench, behind a stone wall or inside a room. The round detonates just beyond the aiming point. For buildings, this would be a window or door frame, cave entrance or the corner of a building (to get enemy troops thought to be around the corner.)
The XM25 is still a heavy weapon, with the final version coming in at 12 pounds. The 25mm shells weigh over half a pound each. On the plus side, there is already a 25mm armor piercing round (using a shaped charge capable of penetrating over 50mm of armor) available. This makes the M-25 capable of knocking out light armored vehicles.
The U.S. Army has fired over 30 million 25mm shells from the cannon on its M-2 Bradley armored vehicles and was satisfied with the lethality of that shell against infantry. Then there are the new versions of 25mm round, like fuel-air explosive (or "thermobaric"). Such a shell would cause greater blast effect in an enclosed space, and actually suck most of the oxygen out of a cave or closed room long enough to make surviving troops at least a bit groggy. This gives the attacking troops an opportunity to rush in and kill the enemy, or take prisoners. In combat, every little advantage helps.
The XM-25 will probably show up in Afghanistan first. Most of the combat there is out in the country, and the enemy like to use their PRGs (rocket propelled grenades) as artillery. An experienced RPG user can hit a stationary target at 500 meters, and come fairly close at a kilometer. The XM-25 provides similar capabilities, and with every infantry squad (of 10-11 troops) having one, the enemy will soon know about it. That's because hiding behind rocks, trees, walls or in caves will no longer protect you. The 25mm smart shells cost $25 each.