Let it Die PC # White Steel Nightmare
Salvage Gear and Repair it or Build up a Decent Body Armor.
After you got some Forcemen Pieces and weapons you can beat the 41 and the 51 way more easier. Using a Shooter Tier 5 or a Tier 6 all rounder doesen't make a Difference here
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https://www.youtube.com/watch?v=vmHoL4-1jyA
Let it Die ? Black Thunder Hard Mode RN-Gun No DM - (Body/Legs Blueprints and costs) with this method you can farm him without wasting DM's. Nightmare should work too with that.
You can get everything from him in hard mode except his sword and 44ce Metal.
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https://www.youtube.com/watch?v=O5GRLOYyQ1c