40 Round Mag attachment in MW4
The 40 Round Mag is a magazine attachment that community sites list for 3 weapons: Hyeon Burst, Axion, and ISO Nightshade. CODMunity lists a stat change on 3 of them; the largest is magazine size +33% on the Hyeon Burst (better). It is in 4 popular builds that CODMunity lists.
Community-reportedggranked and CODMunity, read . Unverified, not Activision data.
Weapons that can equip the 40 Round Mag
Activision publishes no compatibility list; 2 community sources report these 3 weapons. No weapon level is reported.
| Weapon | Class | Weapon level | Stats with a listed change |
|---|---|---|---|
| Hyeon Burst | Assault Rifle | magazine size (large, better), total rounds (large, better), reload time (moderate, worse), ADS speed (small, worse), ADS out speed (small, worse), ADS movement speed (minor, worse), crouch movement speed (minor, worse), and firing movement speed (minor, worse), and 5 more | |
| Axion | Assault Rifle | magazine size (large, better), total rounds (large, better), reload time (moderate, worse), ADS speed (small, worse), ADS out speed (small, worse), crouch movement speed (small, worse), ADS movement speed (small, worse), and firing movement speed (small, worse), and 5 more | |
| ISO Nightshade | SMG | magazine size (large, better), total rounds (large, better), reload time (small, worse), ADS speed (small, worse), ADS movement speed (minor, worse), crouch movement speed (minor, worse), firing movement speed (minor, worse), and ADS out speed (minor, worse), and 5 more |
What the 40 Round Mag changes
Percent changes are relative to the base value with nothing attached (CODMunity, read November 4, 2026).
| Weapon | Stat | Base | With it | Change |
|---|---|---|---|---|
| Hyeon Burst | Magazine size | 30 rounds | 40 rounds | +33% (better) |
| Reload time | 3400 ms | 3876 ms | +14% (worse) | |
| ADS speed | 275 ms | 283 ms | +3% (worse) | |
| ADS movement speed | 2.36 m/s | 2.31 m/s | −2% (worse) | |
| Movement speed | 4.58 m/s | 4.53 m/s | −1% (worse) | |
| Sprint speed | 6.07 m/s | 6.01 m/s | −1% (worse) | |
| Axion | Magazine size | 30 rounds | 40 rounds | +33% (better) |
| Reload time | 3333 ms | 3733 ms | +12% (worse) | |
| ADS speed | 260 ms | 276 ms | +6% (worse) | |
| ADS movement speed | 2.41 m/s | 2.34 m/s | −3% (worse) | |
| Movement speed | 4.62 m/s | 4.53 m/s | −2% (worse) | |
| Sprint speed | 6.11 m/s | 5.99 m/s | −2% (worse) | |
| ISO Nightshade | Magazine size | 30 rounds | 40 rounds | +33% (better) |
| Reload time | 3267 ms | 3463 ms | +6% (worse) | |
| ADS speed | 240 ms | 247 ms | +3% (worse) | |
| ADS movement speed | 3.20 m/s | 3.14 m/s | −2% (worse) | |
| Movement speed | 4.80 m/s | 4.75 m/s | −1% (worse) | |
| Sprint speed | 6.33 m/s | 6.27 m/s | −1% (worse) |
Smaller changes are left out of the table: 7 other stats on the Hyeon Burst, 7 other stats on the Axion, and 7 other stats on the ISO Nightshade.
Changes across weapons
The stats it changes on 3 weapons, with the lowest and highest change.
| Stat | Weapons | Lowest change | Highest change | Verdicts |
|---|---|---|---|---|
| Magazine size | 3 | +33% | +33% | 3 better, 0 worse |
| Reload time | 3 | +6% | +14% | 0 better, 3 worse |
| ADS speed | 3 | +3% | +6% | 0 better, 3 worse |
| ADS movement speed | 3 | −3% | −2% | 0 better, 3 worse |
| Movement speed | 3 | −2% | −1% | 0 better, 3 worse |
| Sprint speed | 3 | −2% | −1% | 0 better, 3 worse |
| Total rounds | 3 | +33% | +33% | 3 better, 0 worse |
| ADS out speed | 3 | +2% | +5% | 0 better, 3 worse |
| Crouch movement speed | 3 | −4% | −2% | 0 better, 3 worse |
| ADS gun bob | 3 | +2% | +3% | 0 better, 3 worse |
| Firing movement speed | 3 | −3% | −2% | 0 better, 3 worse |
| Strafe speed | 3 | −2% | −1% | 0 better, 3 worse |
| Tactical sprint speed | 3 | −2% | −1% | 0 better, 3 worse |
How it ranks among magazine attachments
Its largest change on each weapon, compared with the other magazine attachments the source lists that stat for.
- Hyeon Burst: its large magazine size change (better) is the weakest of 2 magazine attachments.
- Axion: its large magazine size change (better) is in the lower half of 3 magazine attachments.
- ISO Nightshade: its large magazine size change (better) is the weakest of 2 magazine attachments.
Pros and cons the sources list
None reported, which is different from having none.
Popular builds that use the 40 Round Mag
CODMunity lists 4 popular builds that use it, all for Multiplayer. The styles are Mobility and Versatile. The same builds also use muzzle, rear grip, stock, laser, underbarrel, and optic attachments.
| Weapon | Mode and style | Tier | Other attachments | Builder |
|---|---|---|---|---|
| Hyeon Burst | Multiplayer, Mobility | Very good | Muzzle: FSS IS300, Rear Grip: HYN-Meipeul, Stock: Mugi BAL-202 Stock, and Laser: SZ Gen.6 PEQ | Open in the builder: Hyeon Burst, Mobility |
| Hyeon Burst | Multiplayer, Mobility with Apex Attachment | Very good | Muzzle: FSS IS40, Underbarrel: FSS Fireline Grip, Stock: Mugi BAL-202 Stock, and Laser: SZ Gen.6 PEQ | Open in the builder: Hyeon Burst, Mobility |
| ISO Nightshade | Multiplayer, Versatile with Apex Attachment | Absolute meta | Muzzle: XRK Herder 40, Underbarrel: FSS Fireline Grip, Rear Grip: Demo STP-1, and Stock: EXP G2-44 Stock | Open in the builder: ISO Nightshade, Versatile |
| Axion | Multiplayer, Mobility | Very good | Optic: ZLR Type C, Muzzle: FSS IS40, 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 40 Round Mag do in MW4?
CODMunity lists 39 stat changes for it across 3 weapons: 6 better and 33 worse. The largest is magazine size +33% on the Hyeon Burst (better).
Which weapons can use the 40 Round Mag?
Community sites list Hyeon Burst, Axion, and ISO Nightshade. Activision has not published a compatibility list.
Is the 40 Round Mag in a popular build?
Yes. CODMunity lists it in 4 popular builds, on Hyeon Burst, ISO Nightshade, and Axion.