I finally broke 1,000 kills on R2, but I still have a long way to go before reaching 10,000 (why the Killing Machine medal in the game is 1,000 kills and why the trophy is 10,000 is weird to me). For now, though, I'm just trying to use Skirmish to reach level 15 so I can get the LAARK and Snake Eyes berserks, then I'll probably start playing Team Deathmatch or regular Deathmatch more.