I'm on my last two penances for Arbites (besides doing 100 missions), any recommendations for Terminus Warrant before I start?

Considering the class, the melee kills seem easy, but its the ranged I'm wondering about. I usually use the heavy hitting weapons like the revolver, shot revolver, and new shotgun, non of which seem the best for getting that awful 3500 at a decent rate. I'd hate to be a shitter dumping an autogun into a pox horde, but if thats the best way then whatever.
Are these penances going to be another slog, or does anyone have any tips?