User blog comment:Seadrus/Boss Killers?/@comment-26336580-20150502213854/@comment-1763304-20150504112828

I've seen 12**** Black HIKS S300 fully upgraded with deadly, adaptive, pinpoint, and tenacious absolutely destroy everything, even hordes of Nightmarish zombies, once.

But I can understand lower grade HIKS S300, or maybe even any HIKS S300, being less effective in Nightmare mode. However, it's the best weapon in the game in my opinion for everything else, and even the bosses in Nightmare mode once you clear out the hordes (if there is one).