First, go to any control point once you have the required materials and craft weapon form Surge. Next, kill 50 Hiss.
You get 3 rounds before you have to reload. Press
to fire, then
again to detonate. Or you can hold
and press
three times to unload all three rounds before you detonate for more damage.
Anyway, a good side mission to do this in is Shum after:
Go to an arcade (make sure you have the don't die assist mode turned on, maybe even one hit kills), then go to the arcade and play Crowd Control. Next, start racking up kills with your Surge. My tracker was at 88% by the time I was done with the mission.
You'll also unlock: