Replace Malignant Force or Hunter Munitions with Primed Firestorm for better trash-clearing capabilities.

[Internal Bleeding] is not good on [Tombfinger], as the forced Impact is only on the direct hits, not the AoE damage, and the direct hits are only a small portion of your total damage.

Riven stat priority: CC = CD > MS > Dmg = FR > Toxin
Riven replaces mod with same stats, in reverse order, just don't replace [Galvanized Chamber].

Grip options: Palmaris for Charged Shots, Tremor for Quick Shots.
Palmaris has same Charge Rate as Brash, a tiny bit more damage and a tiny bit more delay between shots, making it about the same in Charged Shot DPS (less than 1% difference), but also ~10% better at Quick Shots. That's why I'm recommending Palmaris over Brash.

Detailed spreadsheets on part choices can be found in my Modular Weapons Guide: https://docs.google.com/document/d/1-74HS0rFLwRxDG4wz4PBRYEnQP2mzgis9HcD7nYGhKs