Repeating cannon of the type you’re thinking probably can’t be mounted in the small boats the Somali pirates use. The more interesting observation in the linked story is the one concerning probable Somali government connivance (or the connivance of various “moonlighting” Somali “govt” officials). Now that is a connection that should be readily susceptible to western naval/amphibious attack.

Such as the radio traffic center onshore that vectors the pirate craft into position to intercept their targets. A precision airstrike while they are transmitting ought to put a stop to that nonsense for a while.

Small “assault” type carriers in the area, ones with helos and small fast attack craft should do the job nicely. How about setting up a rotation schedule for a permanent presence there — and a turn for the “Dokdo” will provide the ROK navy with valuable “live-fire” experience.