PolarStar F2 + MAXX Model · Alignment Kit V2.1 · M4 AEG HPA

Version 2.1 of the hop-up alignment system, designed for M4 AEG HPA replicas with ICS split configuration and compatible with the ICS lower.
This kit is designed for the PolarStar F2 engine and MAXX Model chamber, providing precise alignment between the nozzle and the chamber to improve feeding consistency and overall system stability.

Compatibility

Component	Compatibility
HPA Engine	PolarStar F2
Hop-up Chamber	MAXX Model
Base Platform	M4 AEG / ICS MPX (BlowBack)
Gearbox	V2 / ICS SPLIT

What’s included

• Rear clip for mounting via rear body pin or fixed stock.
• Base with housing for M3 inserts (brass optional).
• Side clip for routing the F2 HPA line.
• Top locking cap specifically designed for MAXX Model chamber.
• Rear plate with mounting point for M5 screw (extra reinforcement).

Installation and setup

1. Printing and preparation

   • Print parts with 65–80% infill.
   • Lightly sand internal and contact areas for a clean fit.
   • To ease maintenance, apply dry lubricant or wax on sliding surfaces.

2. Assembly in the replica

   • Insert the base into the lower and install the M3 inserts.
   • Position the rear clip aligned with the rear body pin or stock mounting point.
   • Install the MAXX Model chamber with the inner barrel; the top cap locks the assembly and ensures proper centering.
   • Route the HPA line from the PolarStar F2 through the side clip to avoid friction or sharp bends.

3. Final fixation

   • Secure the rear plate with an M5 screw and washer for maximum rigidity.
   • Check that the F2 nozzle enters the MAXX chamber centered, with no lateral play.
   • Perform feeding tests and adjust the hop-up accordingly.

Required components (not included)

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

Lower recommendations

For maximum rigidity, using a metal ICS lower is recommended.
If you prefer a printed lower, the following Gearbox V2 Universal Lower models are compatible:

• Version 3
• Version 4.2
• Version 4.3 MTW

You can find them HERE.

3D printing parameters

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

Manuals

Installation and setup manuals are available in the Manuals section of the website or on the project’s Discord server.