[GURPS] Spaceships 1, Missile Launcher Question

[Rowan]

So I'm writing up a small single adventure, where a group of pirates in a small pirate ship get wind of an asteroid claim and decide to move in on it. I wanted something to throw them up against, so I'm using the Sentinel-Class SDP from Spaceships 3 (p.21) as the asteroid claim's guardian that they have to destroy to safely claim jump the asteroid.

I'm trying to get the hang of the combat system, but I'm having a little trouble with the SDP's missile launchers when trying to figure out the Range for the Launchers on the Guns and Launchers table (Spaceships 1, p. 68).

THE SDP has Launchers of the 16cm variety, but the Guns and Launchers table only lists ranges for 20cm Launchers and above. Is it supposed to be inferred that Launchers below 20cm are to use the range listed for 20cm?

Any help's appreciated, thanks. :)