Ok the best weapons are the ak74 with grip and rapid fire and you need scavenger/hardline, warlord/steady aim/slight of hand but just take of the grip and use rapid fire and Hacker/marathon then use semtex, concussion/flash, motion sensor or claymore.
Galil with silencer/ or silencer or red dot/reflex use scavenger/ghost, warlord/slight of hand,hacker then use semtex, concussion/flash, motion sensor or claymore.
Aug with either extended mags/dual mags/silencer/reflex if you combine any two with warlord there all good attachments use Scavenger/hardline, Slight of hand/warlord, Hacker/marathon then use semtex, concussion/flash, motion sensor or claymore.
If you can quick scope in Black ops like me use L96 with variable zoom and Ghost/scavenger(I prefer ghost so you can sneak up on enemys) Hardened or steady aim, Hacker then use tomahawk, concussion/flash, motion sensor or claymore.
There is more but I'm currently testing them to see how good they are