One of the most popular, and widely used infantry weapons in Iraq, gets hardly any attention at all. This is the M100 Grenade Rifle Entry Munition (GREM). This is a rifle grenade, fired from the barrel of an M-16 or M-4, to knock down a door with the same efficiency as battering rams. GREM has a one foot rod in front, giving the proper stand-off for the explosive charge to literally "punch" the door down. Troops like GREM because it's light, reliable and almost always takes down the door it is aimed at, even reinforced metal ones. Thus a soldier can aim GREM at a door at the end of a corridor, without getting close enough to get hit by enemy fire. GREM isn't sexy as weapons go, but given the large number of "no-knock" raids, and urban combat, in Iraq, it is a heavily used one. Work is under way to create a 40mm version of GREM, that can be fired from a 40mm grenade launcher.