FSS IS40 attachment in MW4
The FSS IS40 is a muzzle attachment (“Light Silencer”) that community sites list for 4 weapons: Han 86, M4, Hyeon Burst, and Axion. CODMunity lists a stat change on 4 of them; the largest is damage range −10% on the Axion (worse). It is in 5 popular builds that CODMunity lists.
Community-reportedggranked and CODMunity, read . Unverified, not Activision data.
Weapons that can equip the FSS IS40
Activision publishes no compatibility list; 2 community sources report these 4 weapons. No weapon level is reported.
| Weapon | Class | Weapon level | Stats with a listed change |
|---|---|---|---|
| Han 86 | Assault Rifle | damage range (small, worse) | |
| M4 | Assault Rifle | damage range (moderate, worse) | |
| Hyeon Burst | Assault Rifle | damage range (moderate, worse) | |
| Axion | Assault Rifle | damage range (moderate, worse) |
What the FSS IS40 changes
Percent changes are relative to the base value with nothing attached (CODMunity, read November 4, 2026).
| Weapon | Stat | Base | With it | Change |
|---|---|---|---|---|
| Han 86 | Damage range | 100% | 93% | −7% (worse) |
| M4 | Damage range | 100% | 92% | −8% (worse) |
| Hyeon Burst | Damage range | 100% | 91% | −9.5% (worse) |
| Axion | Damage range | 100% | 90% | −10% (worse) |
Changes across weapons
The stats it changes on 4 weapons, with the lowest and highest change.
| Stat | Weapons | Lowest change | Highest change | Verdicts |
|---|---|---|---|---|
| Damage range | 4 | −10% | −7% | 0 better, 4 worse |
How it ranks among muzzle attachments
Its largest change on each weapon, compared with the other muzzle attachments the source lists that stat for.
- Han 86: its small damage range change (worse) is the weakest of 2 muzzle attachments.
- M4: its moderate damage range change (worse) is the weakest of 3 muzzle attachments.
- Hyeon Burst: its moderate damage range change (worse) is the weakest of 3 muzzle attachments.
- Axion: its moderate damage range change (worse) is the weakest of 3 muzzle attachments.
Pros and cons the sources list
None reported, which is different from having none.
Popular builds that use the FSS IS40
CODMunity lists 5 popular builds that use it, all for Multiplayer. The styles are Mobility and Versatile. The same builds also use optic, magazine, stock, laser, and underbarrel attachments.
| Weapon | Mode and style | Tier | Other attachments | Builder |
|---|---|---|---|---|
| Han 86 | Multiplayer, Mobility | Very good | Optic: ZLR Type C, Magazine: 45 Round Mag, Stock: Meiko L9P-Fold, and Laser: Schlager VISIV-5 | Open in the builder: Han 86, Mobility |
| M4 | Multiplayer, Mobility with Apex Attachment | Meta | Optic: ZLR Type C, Underbarrel: Hurricane Grip, Stock: No Stock, and Laser: SZ Gen.6 PEQ | Open in the builder: M4, Mobility |
| Hyeon Burst | Multiplayer, Mobility with Apex Attachment | Very good | Underbarrel: FSS Fireline Grip, Magazine: 40 Round Mag, Stock: Mugi BAL-202 Stock, and Laser: SZ Gen.6 PEQ | Open in the builder: Hyeon Burst, Mobility |
| Axion | Multiplayer, Versatile | Absolute meta | Optic: ZLR Type C, Underbarrel: FSS Fireline Grip, Stock: Cronen Blackstone-6P, and Laser: XRK Clutch-LS | Open in the builder: Axion, Versatile |
| Axion | Multiplayer, Mobility | Very good | Optic: ZLR Type C, Magazine: 40 Round Mag, Stock: XRK Relay 7, and Laser: Schlager VISIV-5 | Open in the builder: Axion, Mobility |
Builds are community-reported and unverified.
Frequently asked questions
What does the FSS IS40 do in MW4?
CODMunity lists 4 stat changes for it across 4 weapons: 0 better and 4 worse. The largest is damage range −10% on the Axion (worse).
Which weapons can use the FSS IS40?
Community sites list Han 86, M4, Hyeon Burst, and Axion. Activision has not published a compatibility list.
Is the FSS IS40 in a popular build?
Yes. CODMunity lists it in 5 popular builds, on Han 86, M4, Hyeon Burst, and Axion.