Sparklabs WOLF + PolarStar HopUp · Alignment Kit V2.1 · M4 / AR15 AEG HPA

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

This kit is designed to combine the Sparklabs WOLF engine with the PolarStar HopUp chamber, ensuring a stable position between the nozzle and the chamber. The result is more consistent feeding, reduced lateral play, and an HPA assembly that is easier to maintain and adjust.

The Sparklabs WOLF is a drop-in HPA engine for centerline V2 gearboxes. Its system combines electromagnetic actuators with compressed air and allows advanced configuration of the firing cycle. The PolarStar HopUp chamber uses a TDC adjustment system that applies vertical pressure to the bucking for more consistent hop-up adjustment. [154][153]

Compatibility

Component	Compatibility
HPA engine	Sparklabs WOLF
Hop-up chamber	PolarStar HopUp
Base replica	M4 / AR15 AEG
Gearbox	Standard V2
Gearbox type	Centerline

This kit is designed for centerline V2 gearboxes. It is not suitable for offset-nozzle configurations without specific modifications. [157]

What's Included

• Rear clip for mounting via the rear pin or fixed stock.
• Base with mounting points for M3 inserts.
• Side clip to guide the HPA line.
• Upper front locking cap for the PolarStar HopUp chamber.
• Rear plate with an M5 screw mounting point.

Installation and Adjustment

1. Printing and Preparation

   • Print the parts with an infill of 65% to 80%.
   • 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

   • Insert the base into the lower receiver and install the M3 inserts.
   • Install the Sparklabs WOLF in the V2 gearbox.
   • Install the PolarStar HopUp chamber with the inner barrel.
   • Position the rear clip, aligning it with the rear pin or stock mounting point.
   • Route the HPA line through the side clip to prevent rubbing and kinks.

3. Final Securing

   • Secure the rear plate with an M5 screw and washer to increase rigidity.
   • Check that the WOLF nozzle enters the chamber centrally, without rubbing or excessive force.
   • Perform dry feeding tests before fully closing the replica.
   • Adjust the hop-up using the chamber's TDC system according to the bucking and 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 securing

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%

Manuals

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