GATE Pulsar D2 + PolarStar HopUp · Alignment Kit V2.1 · M4 / AR15 AEG

Version 2.1 of the hop-up alignment system, designed for M4 / AR15 AEG replicas with a V2 gearbox.

This kit is designed for the GATE Pulsar D2 Rev. 2 HPA engine, a dual-solenoid evolution intended for high-performance configurations, combined with the PolarStar HopUp chamber. The system keeps the nozzle centered relative to the chamber to ensure more consistent feeding and a more rigid assembly.

This combination helps reduce play between the engine, hop-up chamber, and inner barrel. This improves shot-to-shot consistency and makes it easier to fine-tune an HPA setup based on a V2 gearbox.

Compatibility

Component	Compatibility
HPA engine	GATE Pulsar D2 Rev. 2
Hop-up chamber	PolarStar HopUp
Base replica	M4 / AR15 AEG
Gearbox	V2
System	HPA
Fire selector	Semi-auto and configurable modes via compatible FCU

This kit is designed for the second revision of the GATE Pulsar D2. Always check that your nozzle, chamber, inner barrel, and bucking are properly adjusted before using the replica.

What's Included

• Alignment base to connect the engine and hop-up assembly.
• Rear clip for mounting via the rear pin or fixed stock.
• Mounting points for optional brass M3 inserts.
• Side clip to guide the HPA tube or line.
• Upper front locking cap for the PolarStar HopUp chamber.
• Rear plate designed for reinforcement with an M5 screw.

Installation and Adjustment

1. Printing and Preparation

   • Print the parts with an infill of 65% to 80%.
   • PLA+ or an equivalent engineering material is recommended.
   • Lightly sand the internal and contact surfaces until a clean fit is achieved.
   • Apply dry lubricant or wax if necessary to facilitate installation and maintenance.

2. Assembly

   • Install the M3 inserts in the base.
   • Install the GATE Pulsar D2 in the V2 gearbox, following the manufacturer's instructions.
   • Install the PolarStar HopUp chamber alongside the inner barrel.
   • Position the base and rear clip, aligning it with the rear pin or stock mounting point.
   • Use the upper cap to lock the chamber in its front position.
   • Route the HPA line through the side clip to prevent kinks, rubbing, or strain on the engine.

3. Securing and Inspection

   • Secure the rear plate with an M5 screw and washer for additional rigidity.
   • Check that the nozzle enters the PolarStar HopUp chamber straight and centrally.
   • Perform dry feeding tests before connecting the air supply.
   • Adjust the hop-up, operating pressure, and FCU settings according to the BB weight being used.

Required Components (Not Included)

• 4× M3 × 4.2 mm inserts
• 4× M3 × 8 SHCS screws
• 1× M5 screw with washer for rear reinforcement
• GATE Pulsar D2 Rev. 2 and compatible electronics/FCU
• PolarStar HopUp chamber, bucking, and inner barrel

Recommended Lower Receivers

A metal ICS lower receiver is recommended to achieve maximum rigidity in demanding HPA configurations.

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.

3D Printing Parameters

• Approximate print time: ~1 h 30 min
• Recommended material: PLA+
• Layer height: 0.10 mm – 0.15 mm
• Recommended infill: 65% – 80%
• Post-processing: Light sanding of fitting surfaces

Manuals

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