Where you find it: Draw a straight line from your home town of Sanctuary down towards the lower half of Fallout 4's map and follow it - you'll eventually end up at a location called ArcJet Systems. The facility is a pre-war munitions manufacturer that supplied the USSR with electronics and weapons. Sat innocently on a table in the rocket control room is the Junk Jet, a one-of-a-king machine that blurs the line between being a traditional firearm and a glorified potato gun. Why you need it: How else are you going to use up all of that garbage that quickly fills up your inventory? Sure, Fallout 4 vastly improves upon the usefulness of junk items by giving you the ability to scrap them for crafting materials, but some items will never be useful. Take, for example, pre-war money: it's utterly useless on its own, but when you consider that the Junk Jet does the same damage regardless of what its loaded with, and pre-war cash has a weight value of 0, you've essentially got yourself a gun with near-limitless ammo.