It's not that they're hard to kill that makes it hard to beat, they're easy to kill, but there's just wayyy too many of them, it's like 10 to 1 most times, and the nade drops just makes it worse. Yes I agree that it's always handy to carry a sniper rifle with you so you can pick off those NPC's on rooftops, but the fireteam mode just seems to need alot of good weapons, but gives you so little rewards at the end, so you don't really have enough to buy those weapons, and you'll get really poor playing it. It's also very time consuming, my record is like 102 tries and cleared twice, takes at least 10 minutes per game, 15+ minutes if you actually reach the town part and still eventually get nexonowned.