The Gage Weapon Pack #01 Add-on for PAYDAY 2 has 10 achievements.
Fill up 72 weapon slots.
While wearing the "Arnold" mask, kill 100 enemies using only the UAR rifle.
While wearing the "Chuck" mask, kill 100 enemies using only the Crosskill pistol.
While wearing the "Dolph" mask, kill 100 enemies using only the AK5 rifle.
Buy the grenade case asset 100 times.
Kill 100 enemies using only the SpecOps submachine gun.
While wearing the "Jean-Claude" mask, kill 100 enemies using only the Kobus 90 submachine gun.
Kill 100 enemies using only the Eagle Heavy rifle.
Throw 100 grenades.
Kill 100 enemies using only the Signature .40 pistol.