A huge amount of kinetic damage is good enough to punch through. Anyone remembers the old Sabots? ''Kinetic''
Depends how far back.
Original, they were a more reliable Harpoon since PD generally could not stop them. It was slow enough that it could be dodged, and often, the AI dropped shields to take a hit... which is exactly what you want if you wanted it mainly to do hull damage. Unfortunately, AI did not use them that way and wasted them on shields if you wanted a reliable hull smasher. It could also crush the armor of weaker ships like frigates or even Medusa.
Second iteration, shotgun spread. More total damage but totally useless because spread was too wide and AI
always dropped shields. Damage to armor was minimal. Only the player would ever take a hit on the shield, and only if he was inexperienced.
Third iteration, back to the original, but much faster. This was the most lethal incarnation. Just as lethal as the first version, but was so fast they were impossible for AI to dodge, and they do not always lower shields. It was an all-purpose missile with low ammo being its only weakness.
Afterwards is probably the modern iteration.