This seems to be the optimal DPS for Clairvoyance. Weakpoint mods should be higher DPS than more crit mods, or gold mods even if not hitting weakpoints all of the time. They will be much higher DPS if a weakpoint can be focused.
Increased magazine size allows for firing a level 3 beam for longer.
Rifling Reinforcement is slightly more DPS (on paper) than Mental Focus. Mental Focus should reach 60 stacks with the expanded magazine, averaging to +45% firearm ATK (and -10% ROF). Mental Focus may be more theorhetical DPS since the stacks will be active for a level 3 beam which deals more damage (45% bonus, but unconfirmed).
However, when used with Viessa, firing will be halted to cast skills, which resets a level 3 beam down to level 2, so that both debuffs can be reapplied.