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Weapon attachments (NAS)

The New Attachment System (NAS) is one of 1.13's signature features. Instead of every gun accepting the same handful of generic add-ons, each weapon gets its own set of attachment slots — a rail-covered assault rifle can carry a scope, a laser, a suppressor, a foregrip and an under-barrel grenade launcher at the same time, while a pocket pistol might take nothing more than a silencer. The slots are drawn around the weapon picture in its description box, so you can see at a glance what fits where.

This page covers NAS from the player's side: how slots behave, what the common attachment families do, and how to work the scope-mode toggle in combat. If you want to know how the system is defined in XML (slots, compatibility, incompatibilities), see NAS internals.

Choosing old or new at game start

You pick the attachment system on the New Game screen, combined with the inventory system, via the Inventory / Attachments option:

Option Meaning
New / New (default) New Inventory System + New Attachment System
New / Old New inventory, old-style attachments
Old / Old Both systems as in earlier versions

There is no "Old / New" combination: NAS only works together with the New Inventory System, and it needs a resolution above 640x480 — there simply isn't enough screen space otherwise. At 640x480 the selector is hidden and the game runs Old / Old. See New Game options for the rest of the New Game screen.

Some items are flagged to exist only in one of the two systems, so the arsenal you encounter differs slightly depending on your choice.

Pick once, per campaign

Switching the attachment system in the middle of a campaign is not recommended: attachments can disappear from items they no longer fit.

How slots work

  • Slots depend on the gun. Each slot holds one family of attachment — scope, laser, sight, stock, barrel and so on — and the game shows a slot only if the gun actually accepts an attachment of that family. Which attachment fits which gun is defined per gun in the game data (Attachments.xml), so a sniper rifle grows a slot for big scopes while a machine pistol doesn't.
  • Big slots exist for bulky attachments that would not fit a normal slot.
  • Attachments can bring their own slots. The classic example is an under-barrel grenade launcher: attach it to a compatible rifle and its launcher slot appears on the rifle's panel, into which you then load a grenade. Any attachment that itself accepts attachments works this way.
  • Some combinations are still forbidden, even when the slots are free. NAS keeps an incompatibility list for pairs that make no sense together — for example, a 10x sniper scope cannot be combined with a reflex sight.
  • Merges still exist. Changing a gun's caliber (barrel/conversion kits) is still done by merging items, not by attachments. NAS checks merge results for validity.
  • Tooltips help. NAS added many attachment tooltips, and in Bobby Ray's web shop you can hover over a weapon to see a list of attachments it can take (controlled by BOBBY_RAY_TOOLTIPS_SHOW_POSSIBLE_ATTACHMENTS in Ja2_Options.INI).

Handling attachments quickly:

Action Effect
Hold Ctrl + left-click Auto-attach/merge the item on your cursor to an applicable item
Hold Alt + left-click Swap an attachment with the item on your cursor, without opening the description box
Shift+F Remove all removable attachments and unload all weapons in the sector inventory

The mouse shortcuts also work in the strategic map and sector inventory. If you keep stripping loot by accident, Shift+F can be limited to unloading only with SHIFT_F_REMOVE_ATTACHMENTS = FALSE in Ja2_Options.INI. The full list of controls is on the hotkeys page.

The attachment families

Reflex and match sights

Reflex sights make the weapon faster to aim — great for close, fast fights. Match sights increase weapon range slightly, but only a few weapons can mount them.

Scopes

Scopes come in several magnification levels and give a vision range bonus while the weapon is raised (press L to look and ready your weapon — some bonuses only apply with a raised weapon). Higher magnification means a bigger bonus, but also:

  • More tunnel vision. While scoping, your merc sees far but narrow — cover your sniper's back.
  • A longer weapon is required. Not every scope fits every gun. As a rule of thumb: a 10x sniper scope only fits sniper rifles, a 4x or 7x fits assault rifles, and pistols or SMGs take at most a 2x — if they can mount a scope at all.
  • Weak up close. Scopes carry a base chance-to-hit penalty and an increased minimum range, so they leave you at a disadvantage in close-quarters combat.

Scopes also change how far you can aim: with the default settings, better scopes allow more aim clicks (very-high-power scopes up to 8, high-power 7, medium 6, less than that 5), also depending on the gun type and whether you use a bipod. The number of aim clicks you get depends on whether you are actually using the scope — see the scope modes section below. High-power scopes and up suffer a to-hit penalty when aiming from a prone position. How aiming and scopes interact with your final chance to hit is covered on the NCTH page.

Suppressors and flash suppressors

These make your weapon stealthier. A flash suppressor eliminates the muzzle flash that reveals the shooter's position when firing. Full suppressors (silencers) — available in pistol, assault rifle and sniper rifle sizes — eliminate the flash and dramatically reduce the weapon's loudness, at the cost of slightly reduced damage. Pair them with cold-loaded ammo for very quiet incursions.

Folding and retractable stocks

Attach one to a fixed-stock rifle or SMG and the weapon becomes faster to bring to the ready position, at the cost of a small to-hit penalty. Most weapons accept either a folding or a retractable stock, not both — and many guns have one built in already, as shown in their item picture.

Foregrips, grippods and bipods

A foregrip improves autofire accuracy — if your sprays keep missing, this is the first thing to bolt on. Some guns have one built in (check the gun's picture). Bipods make the weapon slower to ready and factor into how many aim clicks you get; grippods sit in the same family and were rebalanced to have lower penalties than bipods.

Trigger groups

Some guns have burst fire, some have autofire, some have both — and some have neither. A trigger group adds a three-round-burst mode to compatible weapons that lack it.

Laser aiming modules and flashlights

Lasers improve your chance to hit, but only within a limited range — beyond it they are not much use. The LAM-200 additionally improves night vision. The trade-off: lasers and flashlights reduce your camouflage and stealth, making your merc easier to spot.

Under-barrel weapons

Under-barrel grenade launchers (UGLs) attach to compatible rifles in their own slot and add a launcher slot that holds the grenade itself. Launchers can even take multiple launchable slots, making multi-shot launchers with separately loaded grenades possible. In combat, press B to cycle the firing mode of your primary weapon through burst / auto / under-barrel — the last one fires the UGL instead of the rifle.

Every attachment has a drawback

Because NAS lets you stack far more attachments than the old system, the item set was rebalanced when NAS was introduced so that every attachment costs you something. The design intent, per the NAS documentation:

Attachment Drawback
Scopes Base CTH penalty and increased minimum range — long-range tools only
Silencers Small damage penalty
Magazine extenders Small CTH penalty (heavy), but detachable
Lasers and flashlights Reduce camouflage and stealth
Bipods Higher weapon-ready cost
Rod & Spring Reliability penalty
Folding stocks Slightly higher to-hit penalty
Trigger group Small CTH penalty (and no longer adds reliability)

Exact numbers depend on your 1.13 version and any mod's item data — read each attachment's description box in game for the current stats.

Scope modes in combat

A gun with a variable scope or multiple sights attached does not have to use the biggest optic for every shot. Press . or Q in tactical to cycle through the weapon's available scope/sight modes (and, on guns that support it, alternative weapon-holding modes). This is controlled by USE_SCOPE_MODES = TRUE in Ja2_Options.INI.

The practical use: a 10x scope is a liability in a building fight — minimum range, CTH penalty, tunnel vision. Cycle down to the reflex sight or iron sights when enemies get close, and back to the scope for long shots. Your available aim clicks follow whichever sight you are actually using.

Attachments on enemies

Under NAS, enemy soldiers can carry serious hardware: with random equipment they can get up to MAX_ENEMY_ATTACHMENTS attachments on their gun (default 6, usually fewer). To keep looting balanced, each attachment only has an ATTACHMENT_DROP_RATE chance (default 10%) to drop with the weapon when its owner dies — inseparable attachments always drop. Both settings live in Ja2_Options.INI; the file warns that raising the drop rate above 20% unbalances the game unless you also adjust the attachment count.

One more setting worth knowing: USE_DEFAULT_SLOTS_WHEN_MISSING makes the game generate default slots for items that have no NAS data — useful when playing an old XML mod that was never updated for NAS, though expect some odd attachment choices. See the Ja2_Options.INI tour for more.

Modding NAS

Everything above — which attachments a gun accepts (and therefore which slots it shows), where the slots are drawn, and which attachments conflict — is defined in XML and fully moddable. See NAS internals for the data model.

Sources