[1][3] The Scud missiles obtained by Iraq during the Iran-Iraq War did not prove helpful as the range of the missiles were only 300 km (190 mi) and could not reach the Iranian capital Tehran.
[1][2][3] In April 1988 the missile was successfully tested,[1][3] reports suggest that the Iraqis achieved its high range of 800 km (500 mi) by increasing fuel capacity, lengthening the size of fuel tanks, cannibalizing oxidizer and propellant tanks from other Scuds and decreasing the regular Scud Payload from 800 to 140 kg (1,760 to 310 lb).
[1] The Iraqis however did not use it later on due to poor missile guidance and flight instability.
[1] The Iraqis had reduced the payload of the scud missile to about 140–450 kg (310–990 lb), sources suggest that it was chemical/biological warhead capable.
[2] The missile was said to be unstable because it would tumble about its centre of gravity on reentry,[1] it also had poor guidance.