Definition/Scope: (FM 3-23.25) The M136 AT4 is a lightweight, self-contained, antiarmor weapon. It consists of a free-flight, fin-stabilized, rocket-type cartridge packed in an expendable, one-piece, fiberglass-wrapped tube. The M136 AT4 is man-portable and fired from the right shoulder only. The launcher is watertight for ease of transportation and storage. Though the M136 AT4 can be employed in limited visibility, the firer must be able to see and identify the target and estimate the range. Unlike the M72-series LAW and the M141 BDM, the M136 AT4 launcher need not be extended before firing. The AT4 is a development of the 74 mm Pskott m/68 (Miniman), adopted by the Swedish army in 1960’s. Like the m/68, the AT4 was designed by Försvarets Fabriksverk (FFV) and manufactured at their facility at Zakrisdal, Karlstad, Sweden. Though impressed with the AT4, the US Army saw room for improvement, specifically the sights and slings, which were redesigned. Thereafter, the AT4 was adopted by the U.S. Army as the M136. The AT4 operates on the principle of a recoilless weapon, meaning that the forward inertia of the projectile is balanced by the mass of propellant gases ejecting from the rear of the barrel. Since the weapon generates almost no recoil, a relatively large projectile can be fired which would otherwise be impossible in a man-portable weapon. The disadvantage of this design is that it creates a large "back blast" area behind the weapon which can cause severe burns and overpressure injuries both to friendly personnel in the vicinity of the user and sometimes to the user himself. This makes it difficult to employ in confined areas. The problem of back blast has been mitigated recently with the AT4-CS (Confined Space) version, specially designed for urban warfare. This version uses a saltwater countermass in the rear of the launcher to absorb the back blast—the resulting spray captures and dramatically slows down the pressure wave, allowing troops to fire from enclosed areas. To fire, the user must first ensure that no friendly troops or equipment are present in the back blast area. If firing from the prone position (i.e. lying on his stomach) he must also place his legs well to the side to avoid burning himself. He then disengages two safeties, cocks a mechanical firing pin and presses a trigger button. Aiming is accomplished via range-adjustable plastic sights, which are concealed beneath sliding covers for transport. Alternatively, the weapon can carry an optical night sight on a removable mount.
Broader Terms:antitank rocket