Ok, I'll spill the beans... it's its splash dgm.
Of course, I need to do the proper testing to be completely sure, but once you get used to
your torps ranges; you can just own anything with the "nuclear blast" and nullify the dud
chances...
Seriously, I've been quite surprise when damaging ships that avoided my torps.
And on a side note, MN is nice :P
Tell me it isn't beauty =) I <3 my SS3