I've been running nothing but HC KC, and the SWAT setup I like to use is as follows:
Quickdraw, RDS & Stock Lightweight Hardline (This one is optional obviously depending on how well you are at obtaining your streaks), Cold-Blooded Dexterity If I'm not running Hardline then I'll usually put TacMask on.
Also if I'm not running RDS then I'll add another perk.
Does very well except for some of the hipfire battles, it can be slow sometimes.
*isn't sigged* If I wanted a sig, I would have put something here...
Quickdraw is the only attachment the SWAT needs everything else is subjective.
best attachments in my opinion are(in order)
Quickdraw Stock select fire (only if you find yourself clearing buildings alot) mms foregrip Fmj
sights are completely subjective and therefore its up to the user. I put the forgrip on there because it can helo with the mid-far range kills a lot . The top three are obvious and mms is awesome on it because with the penetration buff it is going to kill behind cover and can even 1bk behind medium walls with a headshot without fmj. Fmj is there because it increases on a already good quality but should never be used over mms