Successfully complete the indicated task to unlock the corresponding weapon upgrade for the indicated character for use in any replayed mission:

7.62mm sniper rifle gun camera (Graves): Successfully complete the first mission.
7.62mm sniper rifle suppressor (Graves): Successfully complete three missions.
Automatic shotgun (Graves): Successfully complete eight missions.
Flashbangs (Graves and Lang): Successfully complete four missions.
HEAT rocket launcher (Lang): Successfully complete the first mission.
Incendiary grenade (Lang): Successfully complete five missions.
LMG 5.56mm 200-round magazine capacity (Lang): Successfully complete three missions.
LMG 5.56mm 25% increased rate of fire (Lang): Successfully complete seven missions.
LMG 5.56mm 40mm grenade launcher (Lang): Successfully complete two missions.
LMG 5.56mm Foregrip (Lang): Successfully complete nine missions.
Proximity mine (Graves): Successfully complete six missions.
Shotgun attachment (Graves): Successfully complete two missions.