The
West German-designed
Armbrust ("Armbrust" means
crossbow, and the weapon is sometimes referred to by this name) is a man-portable
anti-tank weapon similar in purpose to a
LAW. Specifically, it is a disposable (one-shot)
recoilless gun, designed to throw a
shaped charge projectile around 300 meters. This
projectile can penetrate around 350mm of
RHA (
tank armor). The weapon itself looks a bit like an abbreviated, sexed-up
RPG; a squat tube sitting atop an integrated firing mechanism, with a pistol grip. The launcher is approximately 850 mm long, weighs approximately 6.3 kg loaded and fires a 67 mm
HEAT round (grenade).
It is notable for its method of neutralizing recoil. Most recoilless guns rely on large gas jets and/or springs to absorb the kickback of the shell's propulsion. The Armbrust uses a countershot system; the reason for this is to avoid complicated spring-loading in a disposable device, as well as the deadly backblast of hot propellant gases produced by a gas-jet recoilless design. Such gases can kill soldiers forced to fire the weapon from enclosed spaces (like, say, a bunker) which renders them useless for closed terrain ambushes or use from fortified positions.
In the Armbrust, the propellant charge sits between two pistons. Ahead of the front piston is the projectile, and behind the rear piston is the counterweighting shot, or countershot. When the weapon is fired, the charge violently expands and pushes both pistons towards the front and rear of the weapon's barrel, respectively. The front piston launches the projectile, which goes its merry way. The rear piston launches a package of plastic strips of equal mass to the projectile. These fly out the back of the gun and flutter to the ground, or at worst rebound off a rear obstruction to shower over the gunner. The effect is to produce a net zero recoil.
In addition, the pistons are stopped by locks at either end of the barrel. This has two effects; one, it prevents either from flying out and becoming a hazard, and two, it traps almost all of the hot propellant gases inside the weapon, preventing them from harming the launching personnel or generating an enormous IR plume which could betray the launcher's location. The plastic countershot remains as plastic strips because the gases don't contact it, rather than fusing into a potentially dangerous solid at their touch.
Although this weapon was pitched to the NATO nations in the mid 1980s, it was apparent that it had some teething problems, mostly stemming from the fact that it was a fairly complex device for a disposable weapon, and it wasn't purchased. The design, however, was sold to Singapore in the early 1990s, where it was refined and improved; there have been variants produced in Singapore for use by the Singapore army and for export. Singapore is phasing out the Armbrust in favor of the Matador LAW.
The Armbrust is on several countries' 'watch list' as a terrorist weapon, due to its usability in an enclosed space and the 'all up' nature of the weapon. It is notable among the man-portable anti-tank weapons for being a gun rather than a rocket launcher.