Israel has developed a cheaper way to deliver very accurate explosives against enemy troops inside buildings, behind cover, or in trenches. The Israeli solution is the MPRS (Multi-Purpose Rifle System) a 750 gram (1.5 pound) device that is attached to the rail on top of assault rifles (like you would a scope). The MPRS has another attachment for the 40mm grenade launcher that many assault rifles have mounted under the barrel. This cable carries data to a special 40mm grenade, programming it to explode at a specific point (inside a room, behind a rock wall, and so on). The MPRS is basically a sophisticated sight, with a laser range finder, a computer, and an automated aiming system. The gunner picks the target, presses a button to have the laser range finder get the range, and then MPRS programs the 40mm shell, which is then fired. The MPRS can put a 40mm grenade through a window at a hundred meters. Unguided 40mm grenades have a range of about 400 meters but accurate fire at longer ranges is possible with MPRS. The 40mm grenade explosion can kill within five meters and wound up to ten meters or more. The “smart” 40mm round costs less than $50 each.
MPRS costs less than $10,000, which is a lot cheaper than the other solution, the $30,000 XM25. Moreover the XM25 is a heavy weapon (5.5 kg/12 pounds). The 25mm shells weigh over half a pound each (270 grams). 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 XM25 capable of knocking out light armored vehicles. 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. With the XM25, hiding behind rocks, trees, walls, or in caves will no longer protect you. There is also a flechette ("shotgun") round. The magazine holds four rounds, which cost, on average, $35 each. The XM25, with its 4x thermal sight, costs $30,000.
Israel can manufacture special 40mm shells with the same capabilities as the XM25 shells and the U.S. Marine Corps, always looking to save some money (which they never have much of), is considering buying the MPRS. It makes a lot of sense because while every squad has at least one soldier carrying 40mm, unguided grenade rounds weigh 540 grams (19 ounces) and you don’t always need that in combat. But when you do you really, really need it. Same with the XM25 but the damn thing weighs 5.5 kg and only fires the 25mm grenades. With MPRS you have the rifleman in a squad with the 1.4 kg M203 grenade launcher attached to his M4 assault rifle (3.4 kg/7.5 pounds) that can also carry the .75 kg MPRS and several of the .54 kg 40mm smart grenades. As needed the MPRS guy has the equivalent of an XM25 but weighing 5.3 kg and able to fire drum grenades as well. The trooper also still has his M4/M16 rifle. This makes a lot of sense to the American marines and many other ground troops as well.