The The Butcher's AK/CAR Mod Pack Add-on for PAYDAY 2 has 8 achievements.
In the Art Gallery job, kill two of the patrolling guards in stealth in the bathroom. Unlocks the "E.M.O. Foregrip" and the "OVAL Foregrip" for the CAR weapon family and the "Aftermarket Shorty" for the PARA submachine gun.