For this you will need to find 3 NPC's and enter point shooting mode. The harder the game's difficulty, the faster the PS meter will burn down, so this is best done on easy if you want it the fastest way. Once in PS you must aim and click at the 3 NPC's heads each and then activate PS. You can tell if it is a headshot by the red 'X', which is a killing shot. If yellow, it will only wound the NPC, which only happens if you aim at their body and not the head. 47 will automaticly shoot all 3 NPC's in the head and this achievement will unlock.