Think of Rapid guns as giant machine guns. The Gatling Cannons are the size
of Main Guns and take up the space and weight of one as well. Even the
smallest 40mm Revolving Gun is rather large for a weapon. However, what rapid
guns lack in range and weight, they make up for with close combat carnage.
Reload times are faster than Machine Guns which means you can shower a close
target with hundreds of rounds in a matter of seconds. They can also be used
to knock out nearby aircraft and set as an auto-fire weapon.
They can be a fun addition to your big hulls, and depending on your style
of play (hit and fade vs. charge!) could be a useful tool. However, they're
too heavy to be a defensive weapon, and too short ranged to be an effective
offensive weapon in most circumstances