PolarStar F2 + PolarStar HopUp · Alignment Kit V2.1 · M4 / AR15 AEG HPA
Version 2.1 of the hop-up alignment system for M4 / AR15 AEG replicas with a V2 gearbox.
This model is designed to combine the PolarStar F2 engine with a PolarStar HopUp chamber in a standard configuration, without direct attachment. The upper cap keeps the chamber in position and helps maintain alignment between the nozzle and the chamber entrance during installation and operation.
The PolarStar F2 uses a dual-solenoid HPA system that allows independent adjustment of nozzle movement and air release. The PolarStar HopUp chamber for M4/V2 platforms uses a TDC adjustment system and is designed for both AEG and HPA configurations. [55][127]
Installation and Adjustment
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Preparing the Parts
- Print the parts with an infill of 65% to 80%.
- Lightly sand the internal surfaces and contact areas.
- Use dry lubricant or wax on sliding surfaces if necessary.
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Assembling the System
- Insert the M3 inserts into the base.
- Install the PolarStar F2 in the V2 gearbox, following the orientation specified in its conversion kit.
- Install the PolarStar HopUp chamber with the inner barrel.
- Fit the upper cap to lock the chamber in place and keep it centered.
- Route the HPA line through the side clip to prevent rubbing and sharp bends.
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Securing and Checking
- Secure the rear plate with an M5 screw and washer.
- Check that the nozzle enters the chamber centrally, without lateral pressure.
- Perform dry feeding tests before using BBs.
- Adjust the hop-up and F2 programming according to your barrel, bucking, and BB weight configuration.
Recommended Lower Receivers
A metal ICS lower receiver is recommended when maximum rigidity is required.
If you prefer to print your own lower receiver, the following Gearbox V2 Lower — Universal Lower models are compatible:
- Version 3
- Version 4.2
- Version 4.3 MTW
You can find them HERE.
