Use the secondary fire of each weapon in the Single Player Campaign

Kill 100 Chimera with headshots in the Single Player Campaign

Kill an Impaler

Complete the Trainyard mission in a single player campaign.

Complete Vengeance on Hardened, Veteran, or Realistic.

Completed Episode 5: "No Going Back"

Kill 75 enemies with the rifle.

Kill 4 enemies with a single grenade in any Operation.

Kill 25 unaware enemies.

Force an enemy to drop dynamite that kills two people when exploding.

In Campaign, unlock all attachments for any weapon.

Collect 25% of all relics.