The blast launchers make for really good cluster munitions. This missile uses 6 of them placed radially to dispense a cloud of contact detonating HEF warheads. This causes a lot more damage than a simple flak warhead of equivalent mass. This is partly due to the fact that your missile doesn't detonate before hitting your target, allowing it to act more efficiently as a KEP and partly due to the submunitions being of higher mass than typical flak while being distributed over a similar area.
They leave predictable star shaped destruction patterns while penetrating their targets (not particularly visible here due to the extent of the damage).
Designing them is easy and just takes a bit of trial and error. Increase the range of your blast launchers until the spread covers whatever targets you expect to be firing at, but doesn't waste any munitions. I would also advise fiddling with the propellant of the launchers, to change the fire rate so there isn't a large gap between the center and the impacts of the submunitions.
You can even take advantage of the fact that missiles accelerate while in the terminal phase to hit your targets with different munitions in whatever order you want (munitions released later will hit sooner).
For example, you can drop nuclear warheads first, frying any surviving internal components located behind the holes made by your submunitions.
The only issue is that the game considers these missiles to be drones, so you must manually order them to follow the greatest source of heat.
I'm going to attempt optimizing it later, right now the total "warhead" mass is 120kg and can reliably kill a stock gunship on the first hit.
Micro drones 4tw !. I've been using a micro drone ( basically my smallest missile ) with a 18x18 cell launching a 0.5 gram osmium needle @ 5 km/s as an anti missile screen. Those things are nasty, they've been tearing upto 4x their numbers.
Basic "drone" stats : 2.2kg F / 110g Me/ 18x18 0.5g blast launcher/ pure pursuit final (75% fuel for final mode ). total dV is about 1.6km/s. @ 4.5g wet accel.