8x Zoom Scope

Put it on the gun that fights from far away and nowhere else. Your duo is farming sulfur in the valley, you are up on the roof with a bolt action, and anyone walking the ridge shows up big enough to hit. That is what 8x is for: spotting a player and landing the shot at a distance where a holosight gives you a dot over a blur.

Its best argument is the research table. Learning it costs 60 scrap, each copy is a pile of high quality metal at a Level 3 workbench, and so when you die on a roam with it, you craft another one that evening. The variable zoom scope does more, anywhere from 4x to 16x, but you cannot research it and it eats more HQM.

On an L96 it is close to mandatory, since many players find that rifle's iron sights hard to use. On the bolt it turns long shots from guesses into hits. Many players also feel a scope makes recoil heavier, so it suits single shots far better than sprays.