firstly if you use BOTH a silencer and cold blooded on a sniper, it will never 1 hit kill.
i recommend:
M21 With silencer
PP2000 Silenced
Claymore
Scavenger (if you are reasonably good you will run out of ammo very fast, so you need scavenger unless its something like S&

)
Cold blooded
Ninja
ACR Silenced
PP2000 Silenced
Claymore
Scavenger
Cold Blooded
Ninja
EDIT:
Never use the famas with cold blooded, if you don't use stopping power the famas goes from the fastest killing assault rifle to the slowest(unless you headshot close range and all 3 bullets hit lol)