So no, it's not simply because I've got the standard barrel mod in storage, there's something else going on, not to mention it only appeared with the Automatron DLC. If it's appearing simply because I have the standard barrel in storage, why on earth would it require Gun Nut 3? At the screen Where do you want to install Windows. These are called combat scopes, and are intended to replace the Vanilla scopes. The Standard Barrel X+ mod appears at the bottom of the list, below the Quad Barrel mod, and though it requires no resources, it does require Gun Nut 3. This mod adds new scopes to the vanilla weapons in Fallout 4, which have 2.5x and 4x magnification. If I had the single barrel mod in storage, I'd have the option to attach the single barrel (which I do) when selecting the single barrel mod itself.

It is useful, for example, to have a 4-barrel-missile-tracking-mod in the shop because then you can upgrade your launchers. the base weapon, any type comes with 'standard' anything. The 'standard barrel modx+' indicates that you have upgraded and that mod is now in the workshop. Mod Description Standard Sight: Standard. The following are a list of weapon mods that can be inserted in the Scope / Sights slot: Sights and Scopes. Sights and Scopes are a Mod Slot for Weapon Mods in Fallout 4.

Originally posted by MageThis:Means you have that mod in the workshop and there are no material requirements. Fallout 4 Wiki will guide you with information on weapons, armor, enemies, perks.

Scope mod fallout 4