GATE Pulsar H + PolarStar HopUp · Alignment Kit V2.1 · M4 AEG HPA

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

This kit is designed to combine the GATE Pulsar H engine with the PolarStar HopUp chamber, maintaining stable alignment between the nozzle and the chamber entrance. Its goal is to reduce play, improve feeding consistency, and keep the assembly securely positioned during use.

The Pulsar H uses a two-stage hybrid open-bolt system designed to increase alignment tolerance and improve overall assembly precision. [256]

Compatibility

Component	Compatibility
HPA Engine	GATE Pulsar H
Hop-up Chamber	PolarStar HopUp
Base Replica	M4 AEG
Gearbox	V2
Platform	M4 / AR15 AEG

What's Included in the Kit

• Rear clip for mounting via the rear pin or fixed stock.
• Base with mounting points for M3 inserts.
• Side clip for routing the HPA line.
• Upper front locking cap for the PolarStar HopUp chamber.
• Rear plate with a mounting point for an M5 screw.
• Alignment guides to maintain repeatable positioning of the chamber, inner barrel, and engine.

Installation and Adjustment

1. Printing and Preparation

   • Print the parts with 65%–80% infill.
   • PLA+ or a material with equivalent strength is recommended.
   • Lightly sand the internal and contact surfaces until a clean fit is achieved.
   • Apply dry lubricant or wax to sliding surfaces if necessary.

2. Gearbox Assembly

   • Install the GATE Pulsar H engine in the V2 gearbox.
   • Insert the kit base and fit the M3 inserts into their designated mounting points.
   • Position the rear clip in alignment with the replica's rear pin or stock mounting point.
   • Install the PolarStar HopUp chamber with the inner barrel.
   • Fit the upper cap to secure the front section and keep the chamber centered.
   • Route the HPA line through the side clip to prevent friction and tight bends.

3. Final Securing

   • Secure the rear plate with an M5 screw and washer to increase rigidity.
   • Check that the nozzle enters the chamber centrally, without friction or lateral pressure.
   • Perform dry feeding tests before adjusting the engine settings and hop-up.

Required Components (Not Included)

• 4× M3 × 4.2 mm inserts
• 4× M3 × 8 SHCS screws
• 1× M5 screw with washer for optional rear fastening

Lower Receiver Recommendations

A metal ICS lower receiver is recommended when maximum assembly 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.

3D Printing Settings

• Approximate Printing Time: ~1 hour 30 minutes
• Recommended Material: PLA+
• Layer Height: 0.10 mm–0.15 mm
• Recommended Infill: 65%–80%

Manuals

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