Long Barrel + Laser Sight + Fast Mags in some combination is my advice. You basically need Scavenger and Secondary Gunfighter though, which imo makes the weapon much less useful than say, the Tac 40 or the B23R.
macarena69 posted... "That's the point. I can do it, you can't stop me, I gain nothing from listening to you, come on me bro"
Concussed targets make for easy headshots. I got the challenge done in just below 250 kills, though my K/D was only about 1.23 with it at that time. The main challenge I struggled with was the Double Kills but the no perks/attachments was pretty tedious.
I'm going to assume your running fast mags & long barrel since its the best combo but dual wield isn't a bad idea since it has fast mags built in.