I don't know how to properly test this but is it possible that you could shoot the npc as soon as you get the rifle, as long as you aim perfectly (through a ridiculous amount of walls and 100s of meters)? I don't know if walls actually stop bullets at all in this game. Could be worth testing, because it may be possible to shoot npcs you need to kill much earlier in the missions than when you can see them. Or maybe there's a limit to it, I don't know. But the bullet in the video above passes through a floor and a door.
Just remembered that I was checking this before. Wallshooting has it's limits and you can't shoot NPCs from other side of the map. Long time ago I tried to find "shortcuts" on New Eden and Electric Sheep, only setup near bench for bartender on ES was successful. In this demonstrated example on "cc_tuto" you killed Shu because distance for bullet to "travel inside walls" is kinda short.
