Salyut 3
Salyut 3 was launched on June 25, 1974. It was another Almaz military space station, this one launched successfully, included in the Salyut program to disguise its true purpose.It attaining an altitude of 219-270 km on launch and its final orbital altitude was 268-272 km. Salyut 3 had a total mass of about 18-19 tons. It had two solar panels laterally mounted on the center of the station and a retactable recovery module for the return of research data and materials. Only one of the three intended crews successfully boarded and manned the sation, brought by Soyuz 14; Soyuz 15 attempted to bring a second crew but failed to dock. Nevertheless, Salyut 3 was an overall success.
It tested a wide variety of reconnaisance sensors; on September 23, 1974, the station's recovery module was released and re-entered, being recovered by the Soviets. On January 24, 1975 trials of the on-board 23mm Nudelmann aircraft cannon (other sources say it was a Nudelmann NR-30 30mm gun) were conducted with positive results at ranges from 3000 m to 500 m. Cosmonauts have confirmed that a target satellite was destroyed in the test. The next day, the station was ordered to deorbit.