Version 2.1 of the hop-up alignment system, designed for M4 AEG HPA replicas using:
- PolarStar F2 engine.
- MAXX Model chamber designed specifically for M4 AEG platforms.
This kit ensures solid and precise alignment between the F2 nozzle and the MAXX chamber, reducing feeding variations and improving shot-to-shot consistency in high-performance HPA configurations. It is compatible with both standard V2 gearboxes and ICS split platforms.
Compatibility
| Component | Compatibility |
|---|---|
| HPA Engine | PolarStar F2 M4 / V2 |
| Hop-up Chamber | MAXX Model M4 AEG |
| Base Replica | M4 AEG |
| Gearbox | V2 / ICS SPLIT |
What the kit includes
- Rear clip for mounting via rear pin or fixed stock.
- Base with housing for M3 inserts (optional brass).
- Side clip for routing the HPA line.
- Front locking top cap compatible with the MAXX chamber geometry.
- Rear plate with mounting point for an M5 screw providing additional rigidity.
Installation and adjustment
-
Printing and preparation
- Print the parts with 65–80% infill.
- Lightly sand internal and contact areas for a clean fit.
- You may apply dry lubricant or wax on sliding surfaces to facilitate maintenance.
-
Installation in the replica
- Insert the base into the lower and install the M3 inserts.
- Place the rear clip aligned with the rear pin or the stock mounting point.
- Install the MAXX Model chamber with the inner barrel; the top cap locks the assembly and keeps the barrel centered.
- Route the F2 HPA line through the side clip to prevent bends or friction.
-
Final fixation and testing
- Secure the rear plate using an M5 screw with washer to maximize rigidity.
- Configure the PolarStar F2 within the desired pressure range and verify that the nozzle feeds smoothly without lateral play or marks on the BBs.
- Perform firing tests and adjust the MAXX hop-up using the dial/arm according to BB weight and bucking type.
Required components (not included)
- 4× M3 × 4.2 mm inserts
- 4× M3 × 8 SHCS screws
Lower receiver recommendations
It is recommended to use the ICS metal lower receiver for demanding builds.
If you prefer a printed option, the Gearbox V2 Lower "Universal Lower Part" models (Version 3, Version 4.2, and Version 4.3 MTW) are compatible and can be found HERE.
3D printing parameters
- Approximate print time: ~1 h 30 min
- Recommended material: PLA+
- Layer height: 0.10 mm – 0.15 mm
Manuals
Installation and adjustment manuals are available in the Manuals section of the website or on the project’s Discord server.
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