Flooded Arkham hands you a pistol and expects you to make do. Everything else is hidden in specific rooms, safes, and crates, and the attachments are the real progression system hiding inside the weapon list. There are five base-campaign weapons, each with two attachments, for ten parts in total. A weapon you walk past is not necessarily lost, but guides disagree on whether weapons are missable, and everyone agrees there is no chapter select, so the safe rule is to pick every weapon up the moment you see it.
At a glance
Weapons: 5 base-campaign guns. Parts: 10, two per weapon. A crate, safe, or puzzle room holds each part.
E.R.C. rule: one single-use Activator Pen opens one Emergency Relief Crate. No pen in your inventory means no crate, not a missing story flag.
No chapter select: once a chapter closes, its rooms close with it. Sweep a chapter before its final exit.
One choice is permanent: the Printing Press pays either a shotgun part or Dream Essence, and it cannot be solved twice.
Pickup confirmation: each world-found weapon is reported to fire an achievement on pickup, which is the fastest audit that you got it.
Equalizer Mk. II, the starting pistol
The Equalizer Mk. II is in your inventory from the start, in Chapter 1, so there is nothing to hunt down. Treat it as the routine weapon: cheap to feed, always available, and the right answer for enemies you can handle without spending a scarce shell. Its two attachments are Voss’s Compensator, in the Emergency Relief Crate in the Registry of the Library Annex, with the pen in Study 1, which steadies aim under pressure, and Voss’s Target Grip, in the safe in Room 301 of Devil’s Reef Hotel, which adds a perfect-shot timing marker to the crosshair.
The Room 301 safe code is 2137, and it comes from the lyrics to Baby, One More Tide in the Investigation menu, where four highlighted words each stand for a number: a bat’s two wings, one tail, an octopus’s three hearts, and the seven deadly sins, read in the order they appear. Do not leave the hotel without opening it, since the grip is the pistol’s only timing aid and the hotel chapter will not reopen.
Field Surgeon, the Chapter 2 shotgun
The Field Surgeon pump-action shotgun is in Chapter 2, The Wake-Up Call, inside the saloon on Sentinel St, past the safe room, mounted on a wall rack behind the bar. The saloon does not open on your first pass: wait for the creature to smash the door in, follow it inside, then head through the safe room and out the far door. It takes two inventory slots and its shells are expensive to craft, so treat it as a close-range answer rather than a default. In narrow rooms and against enemies that close fast, it earns those slots; as a general-purpose gun, it will starve you.
Its two attachments split across the two kinds of choice this game offers. Cutter’s Sturdy Stock comes from the Printing House press puzzle, and only from the gold solution, which causes more damage to enemies when you shoot them in the back. Cutter’s Tomahawk is in the Emergency Relief Crate at the hospital Reception, with the pen in the Wireless Room, and it adds a melee slash. The press choice is covered in full below, because it is the only weapon part in the game that competes directly with Dream Essence.
The Minuteman, the Chapter 2 submachine gun
The Minuteman submachine gun is in Chapter 2, in the Devil’s Reef Hotel basement at minus 1F, on a table by the ventilation machine, reached after the Staff and Lorelei routes send you into the ventilation side of the hotel. Wade through the flooded corridor, open the gate, and the gun is on the table right before the Generator Room section. Picking it up also unlocks the Mustard Gas crafting recipe automatically, which is worth knowing before you decide the gun is just another bullet hose: it changes what you can craft, not only what you can shoot.
Its attachments are Doyle’s Cold Blood, in the cabinet in the hospital Storage Room at minus 1F, which makes shots slow enemies, and Doyle’s Hot Streak, in the buoy locker in the Fishing Shop on Fish Market 2F, which extends the magazine. Cold Blood has a tool gate: pick up Anti-Rust Acid in the Prosthetics Workshop first, pour it on the rusted Storage Room door downstairs, then open the second gate, whose combination is 1308, with nearby notes each fixing one digit. Hot Streak has a different gate: you need Bolt Cutters from the Fish Market to cut the chain on the room connected to Ezekiel, then match the locked buoy’s four symbols, lighthouse, ropes, starfish, and octopus, in that order, using the fish displays in the shop as the key. Match the shapes on the dial rather than the names, since the artwork is easy to read two ways.
Black Reef Longshot, the hospital rifle
The Black Reef Longshot rifle is in Akeley Memorial Hospital, in the room past the Prosthetics Workshop, on a table beside a corpse. You need the Old Man’s Face Mask first: with it equipped, use the door in the southern part of the Prosthetics Workshop, then take the door on your left. Chapter labels for the hospital stretch vary between chapter lists, but the route through the building is the same. The rifle is the long-range answer and the boss-fight workhorse, and its two attachments are both in Chapter 5, which makes the rifle the weapon most worth finishing before the finale.
Keene’s Timeglass is the rifle scope, in the Emergency Relief Crate in the camp tent in Chapter 5, with the pen in the Portal Room. Keene’s Widowmaker is the recoil pad for stability, in the Emergency Relief Crate up the stairs in the Portal Room cave, with the pen in Upper Storage. Both pens and crates follow the same loop as everywhere else: find the pen nearby, backtrack to the crate, and open it before the final portal, because Antarctica closes once you step through and unopened crates are gone for that playthrough. Fit both before the last fight, since ammunition is plentiful in the final battle and a scoped, stabilised rifle is the cleanest way through it.
Linguist’s Folly, the final grenade launcher
Linguist’s Folly is the last gun, on 1F of the Arkham Fish Market, in the Weighing Station, behind a door held by two starfish locks. Feed the locks Leyden Jars, open up, and the launcher is on the shelf directly ahead. Its attachments are Pyre’s Squid Barrel, a new launcher barrel in a box on a table in Salt Storage, past the 16-button door whose buttons are I, IV, IX, and XVI in any order, and Pyre’s Ocularum, a launcher sight for better accuracy in the safe in the Locker Room on Fish Market 1F, whose code is
1496. Grab the Ocularum when you pass the Locker Room even if you do not own the launcher yet.
Be honest about the launcher before you build around it. Reviewers call it largely useless or nigh-on useless, and the crafting math agrees in one respect: the Alchemical Abundance Talent adds nothing to frag grenades, which stay at one per craft. That does not make the launcher worthless, since a grenade still answers a crowd that bullets cannot, but it does mean the launcher is a specialist tool for crowds and bosses, not a main weapon, and its parts are worth collecting for completion rather than for a damage plan.
The Printing Press choice: gold or silver
The Printing House press needs three Printing Plates, A, B, and C, before it will run. Slot all three, then work the mechanism until every element turns one color. The color you choose is the reward, and the press cannot be solved again. All gold gives Cutter’s Sturdy Stock, the shotgun part that causes more damage when shooting enemies in the back. All silver gives Dream Essence, reported as two points. There is no way to take both in one run, so the choice is a build statement: take gold if the shotgun is your close-range plan, and take silver if you value the tier gate more, since two Dream Essence can be the difference between reaching Intermediate now or after another investigation.
A note on completeness: one further revolver is reported as the reward for completing the Holloway Manor side investigation, for use in the main campaign. This guide counts the five base-campaign weapons above, and the Holloway Manor guide covers that side investigation in full, so treat the revolver as a separate premium-edition reward, not as a sixth weapon missing from the list above.