The Gage Chivalry Pack Add-on for PAYDAY 2 has 4 achievements.
Complete any heist on the OVERKILL difficulty or above with 4 players using only Gage Chivalry Pack masks, primary weapons, melee weapons and Ballistic Vests or heavier armors. Unlocks the "Agatha Knight Veteran" mask, "Bloodied" material and "Agatha" pattern.
Kill 10 shields with a Gage Chivalry Pack melee weapon in a single heist. Unlocks the "Agatha Vanguard Veteran" mask, "Chain Armor" material and "Medieval" pattern.
Kill a black Bulldozer with the Great Sword melee weapon. Unlocks the "Mason Vanguard Veteran" mask, "Forged" material and "Checkered Out" pattern.
Kill a Cloaker with the Javelin throwable. Unlocks the "Mason Knight Veteran" mask, "Scale Armor" material and "Mason" pattern.