@alecunel. Good strat but a couple of changes to consider: try and avoid employing two of the same sort of guy. Replace one of the nobles with a Militia. Militia will not only bring a couple of different skills but they are the best guys with grav guns due to a faster skill gain in core skills (ie they aim faster). The king of weapons is the bowgun with autofire and fire rate mods on it. My L50 bowgun fires 11.9 shots a second, does 400 damage (so at Level 300, just about everything dies with a single hit), and the shots go through things, so you dont so much aim as spray the environment :) Try for a rifle-skilled guy next time!
glitch! if you destroy the chest on the second level then die and continue and go on level 2 then a better weapon is in the box i have done this 4 times