Just a version I devised from testing around in actual combat. Haven't actually built it for myself yet, but I could see it working.

Pretty Forma cost heavy.
[Vile Acceleration] is needed for dat sweet fire rate, puncture to synergize with innate high puncture dmg value.

Hunter Munitions, works very well for a gun with big dmg like this - in case that 1 shot isn't enough to kill off whoever's hiding behind that heavy armour.