Guaranteed to crit with every shot, just make sure it's the first shot in the magazine, after dropping [Volt]'s Shield, so that Fractalized Reset can give you the reload speed bonus, giving you another first shot bonus if needed.

Works best with a maxed ability strength [Volt] helminth [Oberon]'s Smite and [Smite Infusion] mod for an additional 321% radiation damage boost.

Typically, one shot is all you need to take out an Eidolon's weak point, or the final killing headshot.