Somebody in the editorial department probably just confused "nano" as in "billionth" with "giga" as in "billion". Anyway, is the 15 GJ/60 cm/4000 m figure above correct, or is the 20 GJ/30 cm/2500 m figure listed on the CIC correct, or what?
The 20 GJ/30 cm/2500 m data comes from the ship/weapons database on the CIC.
BTW: I notice that in your OWN gun chart in the Articles section, the Neutron gun is listed at 15 GJ/40 cm/4000 m as compared to the 15 GJ/60 cm/4000 m you stated in this thread. Which is the correct figure?