polarstar jack silent industries alpha alignment kit

Version 2.1 of the hop-up alignment system, designed for M4 AEG HPA replicas with V2 or ICS split gearboxes using:

• PolarStar JACK Engine (single-solenoid HPA engine, simple, efficient, and widely used).
• Silent Industries ALPHA M4/16 AEG/HPA Chamber (CNC hop-up chamber with TRUE-TDC and precise bucking control).

This kit ensures solid and precise alignment between the JACK nozzle and the ALPHA chamber, preventing misalignment, double feeds, and shot inconsistency—something critical in high-ROF HPA builds.

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Compatibility

Component	Compatibility
HPA Engine	PolarStar JACK
Hop-up Chamber	Silent Industries ALPHA M4/16 AEG/HPA
Base Replica	M4 AEG
Gearbox	V2 / ICS SPLIT

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What the kit includes

• Rear clip for mounting via rear pin or fixed stock.
• Base with housing for M3 inserts (brass optional).
• Side clip for routing the HPA line.
• Top cap for front locking of the ALPHA chamber.
• Rear plate with mounting point for an M5 screw, providing extra rigidity to the assembly.

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Installation and adjustment

1. Printing and preparation

   • Print the parts with 65–80% infill.
   • Lightly sand internal surfaces for a smooth fit.
   • You can apply dry lubricant or wax to ease assembly and maintenance.

2. 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 ALPHA chamber with the inner barrel; the top cap locks and centers the assembly.
   • Route the JACK HPA line through the side clip to prevent bending.

3. Final fixing and testing

   • Secure the rear plate with an M5 screw and washer for maximum rigidity.
   • Check that the PolarStar JACK nozzle enters the ALPHA chamber centered and that feeding is clean during dry and live firing tests.

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Required components (not included)

• 4× M3 inserts × 4.2 mm
• 4× M3 × 8 SHCS screws

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Recommended lower

Using the ICS metal lower is recommended for very demanding builds.
If you prefer to print the lower receiver, this kit is compatible with:

• Gearbox v2 Lower "Universal lower part" Version 3
• Gearbox v2 Lower "Universal lower part" Version 4.2
• Gearbox v2 Lower "Universal lower part" Version 4.3 MTW

You can find them in the products section by clicking Here

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3D printing parameters

• Approximate print time: ~1 h 30 min
• Recommended material: PLA+
• Layer height: 0.10 mm – 0.15 mm

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Manuals

Assembly and adjustment manuals are available in the Manuals section of the website or on the project's Discord server.