In short, yes they did. Called the R-23M, the cannon was installed and tested on the Almaz space station in the 1970s.

Derived from a very powerful revolver-like aircraft weapon, the gun is the only one officially known to have actually been successfully fired in space.

Based on a Cold War-era bomber tail gun cannon, the weapon has remained the subject of much speculation until official records were released a few years ago.

According to these records, the weapon's development was tasked to the Moscow-based KB Tochmash Design Bureau. They quickly assigned their chief engineer in such matters, Aleksandr Nudelman, to also lead the project.

This was the obvious choice for the Soviet Union, as KB Tochmash had made a name for themselves with many technological breakthroughs in aviation weaponry since the Second World War.

The team, after some deliberation, developed a 37/64ths of an inch (14.5-mm) rapid-fire cannon that could, allegedly, hit targets as far as two miles (3.2 km) away. Opinions do vary, but the weapon is said to have been able to fire from 950 to 5,000 shots per minute, launching 200-gram shells at a velocity of 690 meters per second (1,500 miles per hour).

For a space-based weapon, that is more than enough of a punch to make a huge difference. But, firing such a weapon in space has many more variables and potential problems than on Earth.

For example, while such a cannon could be used in a similar fashion to on Earth, i.e., using an optical sight from the cockpit, this did not guarantee a hit. Unless the target was generous enough to approach within your field of fire, you'd need to potentially move the entire spacecraft to center in on the target.

But, according to "Almaz" project veterans, this is exactly the kind of thing that was achieved. They were able to actually pierce a metal gasoline canister target from a mile away (1.6km) during its ground tests.

It would take until the fall of the Soviet Union for further information to come to light about the real extent of the weapon, however. According to these sources, the Soviet Union actually managed to fire the weapon on the 24th of January, 1975, from the Salyut-3 space station (more on the station later).

As this was a completely unprecedented event, officials behind the project could not be entirely sure how it might impact the integrity of the space station. So, the test-firing was scheduled only hours before the official de-orbiting of the station itself.

It also occurred after the crew on board had been returned to Earth a few months beforehand.

To conduct the test, the jet thrusters on the station were ignited at the same time as the cannon was fired. This was to counteract, as best they could, the recoil of the gun, which was very powerful. This is especially the case in near zero-g.

According to various sources, the cannon fired from one to three blasts, reportedly firing around 20 shells in all. All shells reportedly burned up in the Earth's atmosphere.

While the actual results of the test are still classified, it does appear that the later Soviet armed space stations were to be outfitted with missiles rather than projectile weapons. We'll let you conclude why this might have been the case.

In any case, no further armed space stations would be completed by the Soviet Union, with the last armed "Almaz" being permanently mothballed in 1978.

Read more:

https://interestingengineering.com/rikhter-r-23-soviet-union-space