Complete the indicated task to unlock the corresponding weapon.

Weapon	How to unlock
M249	Complete the "Final Duty" assignment during the final Campaign mission.
M412 REX	Complete the "Tombstone Actual" Campaign mission.
Machete	Complete the "A Trapped Wolf Will" Campaign mission.
P90	Complete the "Peace Maker" assignment during the final Campaign mission.
QBZ-95-1	Complete the "To Valhalla" assignment during the final Campaign mission.
Shank	Complete the "Fang Of The Underworld" Campaign mission.