The Gage Spec Ops Pack Add-on for PAYDAY 2 has 4 achievements.
Get 3 headshot kills with 1 shot from any Shotgun using the Donald's Horizontal Leveller barrel ext.
Complete any heist from start to end and kill 200 or more enemies with any weapon equipped with the Reconnaissance Sight on the Very Hard difficulty or above.
Kill 10 enemies in a row, without missing, while switching between the regular sight and the 45 Degree Red Dot Sight after each kill on the OVERKILL difficulty or above.
Kill 50 Snipers with the Arbiter Grenade Launcher while using the standard ammo type.