Why would you not play USC 17? 
Technically accomplished mod, but it makes Corvus too busy and chaotic for my tastes.
Too many factions with wildly varying graphical styles in various states of balance crammed into a tiny system. I really dig the allegiance system, the bosses and all of that, but I prefer to cherry-pick my factions.
Right now its just BRDY+Junk+Valkyrians+Omnifac here.
Anyways, back on topic, I feel like there's a hole for something like a Dual Squall Cannon. I keep wanting a 550-ish range explosive medium ballistic, and the single Squall really doesn't do a
whole lot more dps than an Ichneumon. Keep the range, drop turn rate and accuracy a bit ... you could make it alternate the shots between the barrels so the single-strike stays the same? I find myself mounting Heavy Maulers when I utterly don't need the range just for the DPS without the grievous accuracy of the Assault Chaingun.