These are the requirements for the 10 different assignments that each unlock a new weapon in the upcoming Back to Karkand expansion for Battlefield 3:

FAMAS – “Best Friend Forever
10 Revives
10 Heals

HK53 – “Fixing it”
10 Repairs
1 Kill with the repair tool

QBB-95 – “Let it rain”
20 Kills with Light Machine Guns
2 Mortar kills

QBU-88 – “Specops”
20 Kills with sniper
6 Laser designations

PP-19 – “Familiar Territory”
ARM 10 MCOM stations
10 Flag captures
2 Hours played on Strike at Karkand

L85A2 – “Professional Russian”
100 Assault rifle kills
20 Grenade launcher kills
Win 5 Squad Deathmatch rounds

QBZ-95B – “It goes Boom!”
50 Kills with AT rocket
1 Enemy vehicle destroyed using the repair tool
Win 5 Conquest rounds

MG36 – “Keep your head down”
100 Kills with Light MG
50 Suppression Assists
50 Ammo Resupply Assists

L96 – “Creeping Death”
50 Headshots
50 Spot Assists
5 Knife kills

MK3A1 – “Scarred Veteran”
10 Kills with the PP-19
6 Kills with the DPV Jeep
10 Kills with the BTR-90 APC
2 Hours played on Sharqi Peninsula
2 Hours played on Gulf of Oman