I've had a lot of success flanking rather than being flanked. I've been using a silenced MP7, overkill, type 25 as secondary, frag grenade, and perks. Run out of ammo, just swap guns. Find yourself needing more range than the MP7 can offer, swap to the type 25. Continue flanking around to their spawn points and then slaughter them.
I was using care package, sentry gun, and lightning strike... I don't often get them but when I do they are all together and then I get at least 5-10 kills off the killstreaks