The Naval Autocannon (or NAC), unlike its smaller cousin, uses controlled plasma explosions to fire a shell at enormous muzzle velocities against a target hundreds of kilometers away. The other main difference between naval autocannon and the ground unit is one of scale: The smallest naval autocannon weighs as much as twenty Atlas assault 'Mechs, while the largest weighs as much as a complete Cluster of Dire Wolf assault OmniMechs. The ammunition for these massive WarShip killing weapons is similarly outsized: Each NAC shell weighs between .2 and 1.2 tons. In exchange for the massive weight and bulk demanded by its supporting system, the Naval Autocannon can provide a killing blow to even the largest WarShip or destroy a world via orbital bombardment.
The main disadvantage to the Naval Autocannon is its powerful shell and massive damage potential. Due to the comparatively slow tracking speed of these massive weapons, they are not particularly effective against any spacecraft that masses less than 500 tons, including AeroSpace Fighters. For this reason WarShips frequently employ conventional autocannon types to defend against AeroSpace Fighters. These conventional autocannon could use special munitions, but the larger NAC could not.
Like the autocannons used by ground units, NACs are broadly classified into several categories based on their damage potential:
- Tactical Operations, p. 331, "Naval Autocannon (Capital AC)"
- Technical Readout: 2750, p. 122
- Technical Readout: 2750, p. 122, "Explicitly states that these weapons may only fire on DropShip-sized or larger targets".
- Total Warfare, p. 303, Provides to-hit penalty to capital weapons info.