VFC M4 / HK416 HPA magazine adapter

3D Printed VFC HPA Magazine Adapter
This 3D printed HPA magazine adapter is designed for VFC AR-style airsoft magazines, offering a compact and reliable way to run an HPA setup while retaining key original components.
The adapter accepts an HPA nipple of your choice, allowing compatibility with different hose and regulator preferences. Air is routed through standard HPA tubing, and the system reuses the VFC AR magazine valve head to ensure proper fit and consistent airflow.
A cut-down ball pen spring is used specifically for the magazine release mechanism, providing positive retention and smooth release when installed. Sealing is handled using a 1–2 mm rubber sheet, with super glue used where necessary to reinforce joints and maintain an airtight fit.
Required components:
HPA nipple (user’s choice)
HPA tube
1× M2x20 screw
1× M3x15 screw
VFC AR magazine valve head
Cut-down ball pen spring (mag release)
Super glue
1–2 mm rubber sheet
This adapter is intended for airsoft use only. Final performance depends on print quality, material choice, and assembly precision, making it best suited for experienced HPA users and tinkerers.

Recommended Print Settings
Material: PLA+ or a similarly strong, impact-resistant filament
(PLA+ recommended for ease of printing and adequate strength; PETG or ABS may also be used if tuned correctly)
Infill: 40% (gyroid or cubic recommended for strength)
Layer Height: 0.2 mm
Wall/Perimeter Count: 4–5 walls
Top/Bottom Layers: 6–8 layers
Print Orientation: Print in the intended design orientation to maximize strength around the HPA fitting and mag catch areas
Supports: Only if required by your slicer; avoid supports in sealing or threaded areas if possible
Higher infill and wall count are critical due to air pressure and mechanical stress during use. Weak prints may crack or leak.