Getting Operator Assault Kills in Modern Warfare 3 is a new—and confusing—challenge that arrives with week three of the game. There's no description provided with your task, so you're left to puzzle out what it could mean; "do I have to kill other players with assault rifles?" for example. And since weekly challenges are a big part of unlocking specific aftermarket parts and conversion kits for your guns, you're stuck with it.
This week's aftermarket part is the WSP Akimbo Brace Stock that lets you dual wield the SMG, so it's a pretty desirable unlock to grab. This challenge also involves using a recommended weapon, so you might want to see my SVA 545 loadout or MCW loadout if you haven't got one you like yet. Otherwise, here's how to get Operator Assault Kills in Modern Warfare 3.
How to get Operator Assault Kills
Just like in Modern Warfare 2, an 'Assault Kill' specifically refers to kills you get on players who are defending objectives, though in that game they were called Objective Assault Kills. This means you need to be playing a point-capture based game mode like Hardpoint or Domination. Personally, I recommend Hardpoint, since it's a very kill heavy mode and you instantly capture the Hardpoint if you're the first player to walk into it uncontested.
Most Hardpoints are also very tough to defend, so it's easier to assault them and kill whoever's inside. Sadly, since the challenge says you have to do it with a recommended weapon, you can't just lob in explosives to get those 20 kills, but instead have to use one of the guns marked with the little flame symbol and recommended tag. However, since this seems to encompass all of the best assault rifles, you'll be spoilt for choice.
