In Wolfenstein 2: The New Colossus, the weapon upgrade system works differently than it did in The New Order. Instead of finding the specific item in the game world (like a silencer, for example), you now find and collect generic items called Weapon Upgrade Kits. A Weapon Upgrade Kit can then be applied to any of the weapons you have unlocked in the game, allowing you to tweak your loadout to suit your play style from the very beginning. Of course, you must find a Weapon Upgrade Kit before you can use it.
Below is a list of places where I snagged a Weapon Upgrade Kit. Once you have one, you can navigate to your list of weapons and scroll through to see what you want to alter. Each weapon will have three different modifications you can use.
Note: Weapon Upgrade Kits are funky in Wolfenstein 2. For example, if you miss one in a specific mission, the game tends to put one in the next mission for you to find. This means that you may not find all of the Weapon Upgrade Kits I listed below. That just means you found it previously where as I overlooked it.
Weapon Upgrade Kit Locations
Evas Hammer: There is a Weapon Upgrade Kit to be found in Set Roth’s shooting range on the Evas Hammer. Early in the game you can go into the Ammo Depot, climb the ladder, navigate to the shooting range and drop in. The Weapon Upgrade Kit will be near the table.
Manhattan: Harbor District - As you exit the starting area at the docks you'll find a bombed out building with two Kommandants in it. Look for a fire escape on the side of the building that you can use to climb up a floor. Do so and the Weapon Upgrade Kit will be right in front of you as you head back into the building.
Manhattan: Subway District - During the main Manhattan mission you'll drop into the subway. As you make your way forward you'll come to an office where you can activate the subway train. There is a Weapon Upgrade Kit on the floor inside this room.
Manhattan: Ruins District - At a certain point during your mission in Manhattan you’ll come across a huge Zitadelle enemy. This will be in the Ruins District of the mission. Kill the Zitadelle and head up to the stairs into the building with the Kommandant. When you reach the top, go into the room on the right and find the Weapon Upgrade Kit sitting on the ground by a table. This will be the opposite side of the building from where the Uberkommandant is.
Manhattan: Penthouse District - After you meet Grace and her crew you’ll have to fight off a few waves of Nazi enemies. Grace and team will head for the helicopter, and you’re buying them some time. Take out all the Nazi scum. When the place is clear, you'll find a Weapon Upgrade Kit on the top level and tucked in a corner with some other random stuff.
Evas Hammer: When you return from the Manhattan mission you will be able to visit the Set Roth's kill house on the Evas Hammer. This area is near the shooting range and is guarded by a live trap. Turn the trap off and enter the kill house. There will be two Nazi targets just inside and to the right, and the Weapon Upgrade Kit is sitting on a bench by some lockers.
There are many more Weapon Upgrade Kit locations in Wolfenstein 2: The New Colossus. This guide will be updated to include those in the very near future. For now, though, visit the Shacknews Wolfenstein 2: The New Colossus walkthrough and guide for more helpful information.