ZLR 12GA Ported 21" attachment in MW4
The ZLR 12GA Ported 21" is a barrel attachment (“Heavy Barrel”) that community sites list for one weapon: Rezi 12. CODMunity lists a stat change on 1 of them; the largest is magazine size +67% on the Rezi 12 (better). No popular build that CODMunity lists uses it.
Community-reportedggranked and CODMunity, read . Unverified, not Activision data.
Weapons that can equip the ZLR 12GA Ported 21"
Activision publishes no compatibility list; 2 community sources report this weapon. No weapon level is reported.
| Weapon | Class | Weapon level | Stats with a listed change |
|---|---|---|---|
| Rezi 12 | Shotgun | magazine size (large, better), reload time (large, worse), total rounds (large, better), vertical recoil (moderate, better), horizontal recoil (moderate, better), vertical gun kick (moderate, better), horizontal gun kick (moderate, better), and ADS speed (small, worse), and 8 more |
What the ZLR 12GA Ported 21" changes
Percent changes are relative to the base value with nothing attached (CODMunity, read November 4, 2026).
| Weapon | Stat | Base | With it | Change |
|---|---|---|---|---|
| Rezi 12 | Magazine size | 6 rounds | 10 rounds | +67% (better) |
| Reload time | 6131 ms | 9442 ms | +54% (worse) | |
| Vertical recoil | 98.5 | 84.7 | −14% (better) | |
| Horizontal recoil | 17.4 | 15.0 | −14% (better) | |
| ADS speed | 340 ms | 364 ms | +7% (worse) | |
| ADS movement speed | 3.09 m/s | 3.00 m/s | −3% (worse) | |
| Movement speed | 4.72 m/s | 4.63 m/s | −2% (worse) | |
| Sprint speed | 6.26 m/s | 6.13 m/s | −2% (worse) |
Smaller changes are left out of the table: 8 other stats on the Rezi 12.
How it ranks among barrel attachments
Its largest change on each weapon, compared with the other barrel attachments the source lists that stat for.
- Rezi 12: its large magazine size change (better) is the best of 3 barrel attachments.
Pros and cons the sources list
None reported, which is different from having none.
Popular builds that use the ZLR 12GA Ported 21"
No popular build listed by CODMunity uses the ZLR 12GA Ported 21". That says nothing about how it performs; most listed attachments are in no popular build.
Frequently asked questions
What does the ZLR 12GA Ported 21" do in MW4?
CODMunity lists 16 stat changes for it across 1 weapon: 6 better and 10 worse. The largest is magazine size +67% on the Rezi 12 (better).
Which weapons can use the ZLR 12GA Ported 21"?
Community sites list Rezi 12. Activision has not published a compatibility list.
Is the ZLR 12GA Ported 21" in a popular build?
No. None of the popular builds that CODMunity lists uses it.