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Ships within 48 hours · Estimated delivery Aug 14 - Aug 19
Complete HPA engine kit with dual solenoid closed-bolt system
This lightweight yet durable upgrade is ideal for high-speed AEGs using stronger motors and gear ratios that demand reliable feeding at every cycle
Always use proper eye protection when operating or loading
Ideal for high-performance AEG builds using the Quick Spring Change system
Compatible with most V2 gearboxes including M4
RetroArms CNC Gearbox V2 (8mm) – QSC Best Seller Complete HPA engine kit withThe RetroArms CNC Gearbox V2 (8mm) QSC is a high precision, CNC machined aluminum gearbox shell built for AEG M4, M16, and similar Version 2 platforms. Engineered for maximum strength and performance, it features Quick Spring Change (QSC) functionality, allowing rapid tuning without full disassembly. Made in the Czech Republic, this gearbox delivers exceptional rigidity, smooth gear alignment, and long term reliability perfect for high torque, high
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