Mate I did at Level 22 With perks Centre of Mass, Maths Wrath, Grim Reaper Sprint and Action Girl, using an Anti-Materiel Rifle with Incendiary Rounds the Explosive are no good in the cavern because up close you damage yourself. Yeah I played using a chick thats why its Action girl perk not Action Boy and My girl which I named Dirty Slut is a real mean bitch.

I did at Level 22, and my perks were Centre of Mass, Maths Wrath, Grim Reaper Sprint and Action Girl. I used an Anti-Materiel Rifle with Incendiary Rounds. The Explosives are no good in the cavern because up close you damage yourself.