Personally snd with the mp7 rapid fire with extreme conditioning assassin and dead silence it tears it up..but if your not as good kill confirmed with just about anything. Also specialist gets you mad xp
Okay, I'm not going to tell you to boost like everyone else here. I find it pretty easy to level up playing with my friends in team defender with the specialist strike passage. Specialist helps alot because you get a lot of challenges because you get the challenges for both the strike package, as well as each individual perk's challenges, so it's not anyone new to see 25k exp a game or so in just challenges.