Version 2.1 of the hop-up alignment system, designed for M4 / AR15 AEG HPA replicas using:
- PolarStar JACK engine (drop-in HPA kit, compatible with a wide range of V2 gearboxes with a centerline nozzle).
- RetroArms hop-up chamber for M4/AR15 (high-precision CNC chamber, designed for a solid, stable, and reliable fit in HPA builds).
This kit ensures precise alignment between the JACK nozzle and the RetroArms chamber, reducing play, improving feeding, and providing a more consistent base for HPA setups with V2 split / ICS gearboxes.
Compatibility
| Component | Compatibility |
|---|---|
| HPA Engine | PolarStar JACK |
| Hop-up Chamber | RetroArms M4 / AR15 |
| Base Replica | M4 / AR15 AEG |
| Gearbox | V2 / ICS SPLIT |
What’s included in the kit
- Rear clip for mounting via rear pin or fixed stock
- Base with housing for M3 inserts (brass optional)
- Side clip for routing the JACK HPA line
- Top locking cap for the RetroArms chamber
- Rear plate with mounting point for an M5 screw (extra reinforcement)
Required components (not included)
- 4× M3 × 4.2 mm inserts
- 4× M3 × 8 SHCS screws
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