Unlocked by getting 400 points in the shooting range.
The shooting range is found in the hub area 'Evas Hammer' ('Hammerfaust' in German version). You visit this area between missions. The first opportunity for this is during chapter 'The Reunion'. However, it's easier if you wait until after the story. After beating the game you will return to the hub area and can repeat the shooting range as often as you want. By then you will have upgraded weapons to make things easier.
You actually visit the shooting range automatically during 'The Reunion' chapter. There are two modes: Shooting range (downstairs) + Killhouse (upstairs).
For this you must play the Shooting Range downstairs. You can see targets at different distances going from side to side. Simply hit each target once. It doesn't matter if you do a headshot or destroy the target. The further away the target is, the more points it gives you. Get a total of 400 points for this trophy. I found it easiest with the submachine gun (not akimbo mode). Use hipfire only, don't aim down the sights. For the targets in the far back just keep shooting and wait for the targets to slide into your line of fire.
There are infinite supplies of ammo in the shooting range (pistol ammo is downstairs, all other ammo upstairs). You can restock before each try.
