Make Broadsword, Scimitar, Rapier, and Stiletto Missile Launchers I, II, III, IV, V, and VI (Tech 22) AI base bought. Like, make them all bought in Hyperion. These are the baseline Missile Launchers. They are classified as Common.

Make dropped Missile Launchers (Vulcan, Mira, Jungle, etc) Uncommon. They have minor aug bonuses that make them better.

Make built/uber only dropped Missile Launchers Rare. The aug bonus is better. Inbuilt Missile Launchers (Vega, BanaKingShip, etc) are also Rare.

On a side note: Broadsword IV has a 1.5% chance to drop from NCC-Bulks and a 4% chance from Ismail. Yeahhhhh.