actually, i agree with snail...i usually choose hornets over harpoons if i really need to take care of a turret.
Hornets aren't really good against turrets, because of the crappy Subsystem damage ratings. In all honesty, no other missle though is better for pounding crusiers than Hornets.(Trebs are too bulky, and don't provide an effective enough volume of fire. Tornados are far better for dogfighting, but don't arm properly when fired unlocked. Hornets are brutally effective in this regard.
Though, as far as straight-out turret smashing, trebs do work wonders(My prevoius paragraph was just flat-out attacking a crusier, not disabeling it.), or, really failing that, Rockeyes. Hey, at least you have a use for them. (Plus they make fantastic anti-bomb weapons.)
