It's not a discovery problem, but because of a game bug. Seems that there are some "dead missile zones" where missiles dont do any damage to BS's.
People at digital anvil never corrected that... :(
I use cids. my fighter has one. It lowers the shield of an enemy ship quite fast...
(in fact i was thinking to make a fighter only equipped with tizonas, for the next C vs A battle. (a sort of anti BS-shield fighter)...
(If you find any mistake in my English, please let me know via a PM)
(Really, I speak terrible English, so please, tell me if I make mistakes. I'd like to improve it a bit )