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Home » Accessories & Parts » AEG Internal Parts » Gearbox » Version 2 Gearboxes

Retro Arms CZ Billet CNC 8mm Ver.2 Gearbox Shell for M4 Series Airsoft AEG Rifles
(Model: Split Gearbox / Hop-Up Chamber)

ID: 112017 (GB-RA-6576)
6576
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Color may vary
Retro Arms

$169.00

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Model Options:
ModelSplit Gearbox / Hop-Up Chamber$169.00
ModelSplit Gearbox / Shell Only$110.00
ModelStandard Gearbox / Shell Only$119.00

Description

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Product Description

Features

  • Precision machined from a block of billet EN AW 7075 T651 aluminum
  • Split gearbox design allows easier installation of internal parts
  • Includes Retro Arms CNC aluminum rotary hop-up unit
  • Quick change spring guide system
  • Durable anodized finish
  • Reinforcement in key stress points to counter rapid wear from high performance parts
  • Pre-radiused cylinder windows - helps evenly distribute impact force
  • Deeper wire channels along base of gearbox
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 EN AW 7075 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.
Split gearbox means that this gearbox is designed to have a two part upper and lower. An advantages of having a split gearbox is that it's much easier to install internal parts into the gearbox. During setup of a cylinder set, there is no need to remove the whole gearbox from the receiver and only the upper part needs to be removed as it's mounted on the receiver pin.

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.

15 Customer Reviews

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by Elijah M. on 09/09/2023
"Wonderful gearbox. Used in high-stress build with a DSG and high rating spring. Tens of thousands of shots later, and after hundreds of full auto bursts, opening the gearbox and removing all of the old grease reveals a gearbox as good as new. Incredibly lightweight, yet robust and extremely strong. I ordered black but got sent silver, but can't complain about the quality of life that the gearbox provides with the quick change spring system, for when I need to switch out the spring for my DSG, which I need more of.
by Frank H. on 03/19/2021
"Great gearbox. Was everything I thought it would be.

One small problem though: my buffer tube screw was too long for the QC spring guide that came with this gearbox. It was originally M5 x 50mm, had to grind it down to M5 x 40mm for it to fit correctly. Also if you're gonna remove material to fit bushing/bearings, use a hand tool and manually take off a LITTLE bit at a time. Don't go crazy with it!
by Whit M. on 11/18/2020
"These gearboxes are absolutely beautiful and machined very well. FLT bushings fit flush on both sides although they were extremely hard to fit in the shell, I removed some material from the inside of the bushing holes to accommodate. Everything else fit absolutely fine, almost every part in my gearbox is SHS except the cylinder is LCT and the cylinder head is King Arms. This gearbox is extremely light, very strong and easy to use, with extra features making it easier to tech on. Installed a JeffTron Leviathan as a drop-in fit, aftermarket MOSFETs require no modifications to install. Overall great product! I’ll have a video review up on my YouTube channel Octane Airsoft shortly!

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