It's actually pretty easy, it just depends on the weapons you're playing with. I'm working on my second one right now and I'm already half way with it in just an hour of game play. First time I did it my weapon sucked, I only had a void fusion rifle (rare fusion) in stock lol but I still managed to do pretty well. Basically what I'm saying is, if I was managed to do it with such a crappy weapon, I'm sure you'd be able to, too. - sorry about the triple post, it said "request timed out" so I kept trying to post afterwards.