Wolverine Inferno 2 / Reaper 2 + PolarStar HopUp · Alignment Kit V2.1 · M4 AEG

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

This kit is designed to combine Wolverine Inferno 2 or Wolverine Reaper 2 engines with a PolarStar HopUp chamber, creating a stable connection between the nozzle and the chamber. Proper alignment helps achieve more consistent feeding, reduce lateral movement, and maintain a more consistent seal during firing. Both the Inferno and Reaper are available for M4 configurations with V2 gearboxes; the Reaper Gen 2 features a closed-bolt design and an Air Saver system.

Compatibility

Component	Compatibility
HPA Engine	Wolverine Inferno 2
HPA Engine	Wolverine Reaper 2
Hop-up Chamber	PolarStar HopUp
Base Replica	M4 / AR15 AEG
Gearbox	V2

This kit is designed for the combinations listed above. Always check nozzle travel and alignment before using the replica.

What's Included in the Kit

• Rear clip for mounting via the rear pin or fixed stock.
• Main base with mounting points for M3 inserts.
• Side clip for routing the HPA tube or line.
• Upper front locking cap for the PolarStar HopUp chamber.
• Rear plate with a mounting point for an M5 screw.
• Alignment guides to keep the chamber correctly positioned relative to the 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 only if necessary to facilitate assembly and maintenance.

2. Assembly

   • Insert the base into the V2 gearbox lower.
   • Install the M3 inserts in the designated mounting points.
   • Install the Wolverine Inferno 2 or Reaper 2 engine according to the manufacturer's instructions.
   • Install the PolarStar HopUp chamber with the inner barrel.
   • Fit the upper cap to lock the chamber in place and keep the barrel centered.
   • Route the HPA line through the side clip, avoiding tight bends, friction, or pinching.

3. Final Securing

   • Install the rear clip using the replica's rear pin or stock mounting point.
   • Secure the rear plate with an M5 screw and washer to increase assembly rigidity.
   • Manually check that the nozzle enters the chamber centrally and that there is no lateral friction.
   • Perform feeding tests before fully closing the replica.

Required Components (Not Included)

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

Adjustment Recommendations

• Check nozzle-to-hop-up alignment before performing tests with BBs.
• Adjust the hop-up after confirming reliable feeding.
• If feeding issues occur, check the chamber seating, bucking, barrel position, and nozzle length.
• Alignment is important in HPA engines because it affects feeding, sealing, and overall consistency. [227][234]

Lower Receiver Recommendations

A metal ICS lower receiver is recommended for maximum rigidity.

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.