Innate heat/electric - You honestly can't go wrong with either but I use innate heat to get a crazy viral/heat build with primed heated charge. Electric is also a great proc to run with a viral build, just to be fair.

Potentially Hydraulic Crosshairs/sharpened bullets over Magnum Force especially if you are running crit boosters like adarza/arcane avenger.

[Eject Magazine] is also a great exilus slot choice but may require a forma or swapping out [Magnum Force] (as mentioned above) which is the real weak link in this build.