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SSR4 Mk1 Complete Gearbox Assembly Gen2
$109
A spare reinforced gearbox assembly for both the metal and polymer SSR4 Gen2.
This improved gearbox is more durable and more reliable due to its enhanced ETU and reinforced design, which withstands higher stress.
It comes with 2 different charging handle arms for the different SSR4 Gen2 versions.
If you have the metal SSR4, use the handle with the notch.
If you have the polymer SSR4, use the handle without the notch.
You will get:
- A CNC Compression Assembly (piston, piston head, cylinder, cylinder head, nozzle)
- A 16:1 gear set
- A flat trigger
- A charging handle polymer arm for the polymer SSR4
- A charging handle polymer arm for the metal SSR4
- A Novritsch SSR4 Gen2 ETU
- A gearbox shell including screws and bushings
- A safety assembly including the switch
- A tappet plate assembly
The SSR4 spring and its spring guide are not included.
Assembly and disassembly videos are in our Academy.
Out of stock
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We expect to restock the product:
• SSR4 Mk1 Complete Gearbox Assembly Gen2 in 9 weeks / July 5th, 2026 Please note, there might be unforeseen delays.
SKU: R2008-2
Category: SSR4 MK1 Spare Parts
Description
INNOVATIVE COMPRESSION ASSEMBLY
To ensure optimal airflow, we opted for CNC parts. The piston is equipped with ported CNC machined aluminium head.
The cylinder head is also made of CNC aluminum with a beefy rubber dampening pad with a custom design that makes the system quieter, gives a longer lifetime to the gearbox shell, and correct angle of engagement (AoE). The cuts in the rubber pad give it optimal airflow.


SPEED
To support the high fire rate the ETU is built to withstand, we added fast and durable 16:1 Gears. This ensures smooth and fast action all the way. Also the ETU that is included in this Gearbox assembly allows for all the features like Burst fire, Binarry trigger or Precocking. So that you’ll have the upper hand!
TRICKS FOR LONGEVITY
We needed the SSR4 to be, above all, reliable. To make it happen, we used a few tricks. First and foremost, the SSR4 is fitted with 8 mm bushings. Compared to bearings, they are sturdier and more reliable. Moreover, they offer supreme durability and low friction.
On top of that, we used steel for parts that tend to undergo a good deal of stress and wear. For that reason, you get a steel cylinder, and steel teeth on the piston.

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