New and need help surviving

TLDR: looking for advice for CQC/run and gun build with survivability

Recently got the game, got to level 40 and started leveling my watch, currently at 150

My preferred gameplay is CQC/run and gun

I currently rock the chameleon/dark winter and enjoy these weapons in combination with a auto shotgun

Tried multiple builds: Striker Heartbreaker Hunters Fury

But I can't seem to stay alive for more than 2 seconds before I'm obliterated to knocked and then revived by my hive when killing hunters in heroic countdown/summit or harder difficulty content

I would really appreciate some advice on remaining upright for more than 2 seconds...