M66 naval coilgun

The M66 naval coilgun, commonly referred to as the Ballista, is a weapon system used by the UNSC Navy during the Interplanetary War. These weapons fire 75mm ferric tungsten slugs at a velocity of 100,000 meters per second.
== History ==
The M66 Ballista was standard heavy armament for UNSC Geneva-class battleships. By 2250 these weapons, along with the Geneva-class itself, were considered obsolete.