A Russian duet
The Russians have always been a fan of rapid-fire naval guns going back to the days of Hotchkiss revolving cannons back in the Tsar’s Imperial Navy. In the mid 1970s the Soviets came up with the first operational CIWS system (predating the Dutch Goalkeeper and U.S. Phalanx) when they added a radar, FCS and other local controls to their AK-630 30mm gatling gun mount which had joined the fleet in 1963.
Now, the most recent update to this system is the AK630-M2 “Duet” which debuted in 2007.
With twin superposed 30 mm 6-barreled GSh-6-30 rotary cannon, this Tulamashzavod produced beast drops a theoretical 10,000 rounds per minute though its internal magazine only holds 4,000 rounds at the ready.
Here is a pretty good vid of the Duet in action (its Russian, but you don’t really need to speak it to get the gist).