I've explored [Trumna] a bit. There are 2 variations of this build that I like best. This one is technically the highest DPS I've found, but with reduced ammo efficiency. However, rifle ammo is extremely common, so the efficiency isn't a problem.
An alternate version with nearly identical sustained DPS uses the same polarities, but swaps [Vile Precision] for [Heavy Caliber] (just shift around [Malignant Force] and [Heavy Caliber]).
If you would prefer to have more status chance, you can swap [Hellfire] and [Infected Clip] for the matching 60/60 mods. It'll give you 66% status per projectile but a significant reduction in DPS. Also at this fire rate, even 33% status chance is enough to build up status effects on any targets.