Version 2.1 of the hop-up alignment system, designed for M4 AEG HPA replicas using:
- PolarStar JACK engine (single-solenoid HPA engine, efficient and simple to configure).
- MAXX Model M4 chamber (CNC hop-up chamber with precise hop adjustment, barrel support, and improved air seal).
This kit ensures solid and precise alignment between the JACK nozzle and the MAXX chamber, reducing feeding variations and maximizing the pressure stability typical of HPA systems.
Compatibility
| Component | Compatibility |
|---|---|
| HPA Engine | PolarStar JACK (V2 / M4) |
| Hop-up Chamber | MAXX Model M4 AEG |
| Base Replica | M4 AEG |
| Gearbox | V2 / ICS SPLIT (ICS compatible) |
What the kit includes
- Rear clip for mounting via rear pin or fixed stock.
- Base with housing for M3 inserts (optional brass depending on preference).
- Side clip for routing the JACK HPA line.
- Front locking top cap adapted to the MAXX chamber geometry.
- Rear plate with mounting point for an M5 screw to increase system rigidity.
Installation and adjustment
-
Printing and preparation
- Print the parts with 65–80% infill.
- Lightly sand internal surfaces and contact areas for a clean fit.
- You may apply dry lubricant or wax on contact areas to facilitate assembly and 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 in place and centers the barrel.
- Route the PolarStar JACK HPA line through the side clip to prevent bends.
-
Final fixation and testing
- Secure the rear plate using an M5 screw with washer.
- Configure the JACK engine pressure within your usual operating range and verify that the nozzle enters the chamber centered, without rubbing or forcing.
- Perform feeding tests and adjust the MAXX hop-up until the desired trajectory is achieved.
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 maximum rigidity.
If you prefer to print the lower part, the Gearbox V2 Lower “Universal Lower Part” versions 3, 4.2, and 4.3 MTW are compatible with this kit.
You can find them by searching “universal” at:
https://lab.sychev.xyz/prodcuts?q=universal
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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