Designed to clear rooms with one-shot.
Heavy Caliber is used on purpose to give the multishots additional spread thus better coverage.

Post-nerfs it won't clear rooms with [Primed Firestorm] any more, radius is too low so shifting to higher focused damage.
You can no longer get headshots from radial damage either.

You can get higher dps on paper by pumping fire-rate but you have a limited number of rounds to work with and other than (the likes of) acolytes or liches nothing survives the first shot.

[Bladed Rounds] requires aiming thus the slower homing mode but this lets you jump the damage from 742k to 1.1M for the homing rocket.
There's not a lot of good options left for the final slot.
Tempting to still try [Galvanized Scope] and aim the rockets for headshots but either we're aiming.