This build focuses on the alt-fire grenades, because the grenades AOE have quite a high base damage (about 4x the primary fire) and deal innate corrosive with guaranteed corrosive status.

MOD BREAKDOWN

• Cascadia Flare: provides base damage bonus. Galv Shot doesn't apply to the AOE component of alt-fire

• Galv Diffusion : mandatory multishot

• Primed Pistol Gambit + Primed Target Cracker: mandatory crits

• [Ice Storm] + Pistol Pestilence: Makes viral which boosts dmg to health up to 4.25x at 10 statuses. Ice storm increases mag capacity to 21 and alt-fire consumes 3 ammo, meaning you have 7 shots of altfire rather than 5 per round

• Primed Heated Charge: raw heat damage and helps stack Cascadia Flare

• [Lethal Torrent] + [Accelerated Isotope]: gives fire rate which improves charge rate of altfire too, and also have minor side benefits like multishot and radiation dmg

FLEX OPTIONS

• [Primed Fulmination]: boosts the small AOE from 3m to 4.3m. This seems small but the relative increase to AREA of effect is double (from 28m2 to 58m2).

ARCANE:

• Cascadia Flare, Secondary Outburst, Secondary Fortifier are all good options