Then I guess the enemies heavy ammo is your best bet. Obviously in something like rumble it just is nearly impossible to find a heap of people all in a group, which is why the only rumble clips in this video are sniping clips (and there are very few rumble clips in total even though I've played about 200 matches of the gametype haha)

Oddly enough skirmish is where I get the majority of my multi kills haha

Haha. I can get a few triples and stuff, but only once ever did I get an awesome multi (which is that slayer that I used for the last clip)