The AT-4 Spigot anti-tank guided missile is a second-generation SACLOS-guided tube-launched missile. It was introduced in the Soviet Union in the early 1970s, when the missile system was known as the as the 9K111 Fagot and the missile itself was called the 9M111 Fagot. (AT-4 Spigot is the NATO reporting name.).
The At-4 consists of a preloaded launch tube, a firing post and a sight unit that contains SACLOS guidance electronics.
The launch tube for the AT-4 Spigot is 47.2inches (1200mm) long and weighs 26.5 pounds (12kg). The entire missile system weighs 88.2 pounds (40kg).
Two men are needed to operate the AT-4 - one fires the weapon and the other reloads the launch tube.
The AT-4 Spigot can be fired from the ground or mounted on a vehicle.
Armed with a 4.72inch (120mm) diameter, 6.61lb (3kg) HEAT charge, the AT-4 has a maximum range of 2, 734 yards (2500m) and a velocity of 656ft/s (200m/s). The warhead can penetrate up to 23.6 inches (600mm) of armor.
It is claimed that the Spigot has an accuracy rate of up to 90% against static targets at 2187 yards (2000m).
The AT-4 Spigot was not well known in the West until 1980. NATO observers then realized that the Soviets had been using second-generation SACLOS (Semi-Automatic Command to Line of Sight) guidance and would soon be replacing their older missiles systems, which used first-generation MCLOS (Manual Command to Line of Sight) guidance.
Currently, the AT-4 Spigot is in service with the Russian Army as well as many other armies around the world, including former Soviet republics.