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Retro Arms CZ Billet CNC 9mm QSC Ver.2 Gearbox Shell for M4 / M16 Series Airsoft AEG Rifles

ID: 53853 (GB-RA-CNCV2-9mm)
Retro Arms CZ Billet CNC 9mm QSC Ver.2 Gearbox Shell for M4 / M16 Series Airsoft AEG Rifles
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Retro Arms



  • Precision machined from a block of billet EN AW 7075 T651 aluminum
  • Reduction of wall thickness for greater compatibility with most M4 / M16 receivers
  • Milled ports for improved air flow
  • Quick change spring guide system
  • Conveniently placed porting to easily lubricate gears without gearbox disassembly
  • Opening for releasing anti-reversal latch
  • Reinforcement in key stress points to counter rapid wear from high performance parts
  • Precision CNC machined spring guide included
Unlike most other gearbox shells on the market, the Retro Arms CZ gearbox shells are precision CNC machined out of a solid block of billet AW EN7075 T651 aluminum giving them unmatched durability and resilience. Combined with reinforcement of key stress points and stainless steel connecting bolts, the gearbox shell has undergone extensive stress tests with M160 springs without any signs of wear.

Version 2 Retro Arms gearboxes feature a quick-change ball-bearing spring guide mechanism, allowing spring swaps in a matter of minutes without complete gearbox disassembly.
Compatibility: For Tokyo Marui, G&P, Matrix and other compatible M4 / M16 Series Airsoft AEG Rifles (Modification may be required depending on brand and model)
Material: CNC Billet EN AW 7075 T651 Aluminum
Color: May vary between silver and black

Manufacturer: Retro Arms CZ

Disclaimer: Please use discretion when installing custom parts as fit and compatibility may vary. Some modification may be required. Professional installation recommended.

1 Customer Review

(Write a review)

by Bennett K. on 05/06/2024
"This gearbox is the same quality and precision as all their other gearboxes.
Holds up in a super high-stress build (DMR)
The quick-change spring system is super convenient.

I didn't have the appropriate bit to be able to set the tappet spring pin, so I had to buy one.
(It could come pre-installed, but it isn't for customization purposes.)

5/5 will be buying again for my next build.

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