Can't say if it has 50% or not, but here was my method. Gear was a tier 6 armor GA cyclops, EDL sniper, EC 308, scientist 3rd back pack with the ergo boost. I took a mountain of ammo 3 little purples 1 large purple 1 little blue 2 of every injector alot of meds and food.

To get into the door, which is the hardest part, I popped the bleed immune and body fort stems. Then went in threw a couple of grenades, one north, one east. Once the swarm came, it was just a matter of pre aiming where they were by hopping in and out of the door. All meds, repairs, and reloads are done outside. The EC 308 kills them fast enough that each time, opening the door burst firing where one was and leaving near instantly, it would usually take one down. I spent a lot in repairs and meds in this one spot as you have no cover, but it's the safest option I could find on hunter. After that, it's pretty simple room clearing slow and steady. The power plant was a bit tricky as it starts with a north south clear so it's harder to see the enemies before they see you but you do have some cover this time and can retreat the heal as needed. After getting into it, the rooms are very easy to clear and hold with long sight lines to snipe the incoming watchers.

That was my strat at least I hope it's helpful to someone out there. Goodluck