Black Ops 1 and before ... I was mostly a hardcore tdm, play it safe kind of person.
But in MW3, the PP90 gave me wings and I flew around the map wrecking.
Black Ops 2, the MSMC and PDW-57 lifted me to great heights.
With Ghosts, I've struggled, even gave up on run-n-gun and settled for a more cautious approach around the map. But no longer. I was playing cranked and this one guy had an average chains of 10, holy crap, what was he running with? Well, I found out.
Essentially, he was running mostly speed perks but that wasn't the key. The K7 with rapid fire and the foregrip was. Holy crap this setup melts people at close range. Meh at medium range and sucks at long but I love it. Here's my subtle adjustment to his setup.
The key components:
K7
Foregrip RapidFire
ReadyUp Agility Marathon DeadSilence
[SMGs seem to have Stalker like side-to-side straffing while ADS, use that around corners]
My current setup also has the following, but these can be changed out for different perks like Sleight of Hand or On the Go, or your choice of lethal/tactical:
IED, Concussion, Hardline
Note: Pick up a secondary weapon after you kill someone to give you that longer range shot.