don't you guys have plenty of heavy ammo packs? when we ran out, we would just wait for cooldown to end and try again. we might also just do a run for other ammo during cooldown too so we don't waste time.
I find that I work best killing Skolas while everybody else does what they can. I snipe him to get his health low enough so that I can switch to rockets and end him. Wear some gear that gives extra ammo to both special and heavy. Popping synth is a crutch but I haven't had to do that in the many runs I've had recently. Plus this week is even easier because of black hammer's no reload precision shooting.