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Underlever kit - H22 - (Hera Arms H22 stock)

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  • Regular price £400.00
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Batch 4 is now closed. Next orders for this model will begin around June 2024 for batch 5.

There will be 8 (eight) spare kits available from batch 4 around March 2024. 

Underlevers will now be produced in 3-month rolling small batches, made-to-order, with increased prices to account for much smaller batches, but with accelerated delivery schedules.

Please only order the underlever, any additional items on your pre-order will be removed as we do not wish to hold stock indefinitely.

This Underlever Bolt-Action conversion kit has been specifically designed to be compatible with the Hera Arms H22 stock: 

Best EU shop we've used for the H22 importing to UK:

IF YOU DO NOT OWN THIS EXACT STOCK MODEL, DO NOT PURCHASE THIS UNDERLEVER. This design has not been tested to fit any other style of stock.

Quick Install Guide Video

Huge Launch Event, Demonstration and Testing video!

This kit is a "2nd tier" upgrade kit. It builds on top of several other parts and modifications that must have already been done to your KC-02 before you can install the Underlever. If this is the first time you have seen this kit, we highly advise you to research it before purchasing so you understand how it works and what you need to go with it. This is considered an "Expert Level" kit for people already familiar with working on their KC-02. Here's an example video of a full Underlever KC-02 build process.

Underlevers are NOT COMPATIBLE WITH M4 HPA MAG ADAPTORS. The lever will collide with the magazine.

BUT they are compatible with MP5 mag adaptors like the Tanuki kit :-) as long as the magazine does not protrude backwards from the adaptor.

THE UNDERLEVER ALONE WILL NOT GIVE YOU BOLT ACTION OPERATION. Using it with a standard semi-auto blowback gun will likely result in catastrophic damage and injury. Blowback must be disabled.

The recommended way to install this Underlever also requires a Solid-State Bolt and a Genesis Hop Unit.

If you also want to retain semi-auto operation for your standard bolt carrier to hot-swap with, we recommend purchasing an SSB and a Genesis kit with your Underlever, or an SSB and spare KC-VSR nozzle to convert your existing bolt assembly to VSR type. Then you can simply remove the underlever and swap bolt assembly and charging handle to change the gun back to semi-auto operation as normal. Takes about 5 minutes to do with just 2 tools (4mm allen key and M3 nut driver (linked below)).

If you have any questions then please contact us by Facebook message at

This Underlever kit consists of:

  • Underlever Main hand loop
  • Underlever pivot clamp
  • Triple-bolt bar linkage
  • Sliding-slot bar linkage
  • Bolt-link charging handle adaptor
  • 3 high-grade metal-shielded ball-bearings for the pivot points
  • Assorted nuts and screws for assembly

    The kit will be produced in 7075 aluminium, and is available in our usual range of anodised colours and patterns. If we have spare stock of hop wheels available, and your order includes a Genesis hop wheel, we will also anodise the hop wheel to match your underlever kit. Otherwise you will receive a standard black hop wheel.

    The Underlever itself is compatible with the standard bolt carrier and hop unit, as long as you disable the blowback on your standard bolt carrier. Achieving this is a complicated task in itself, which is why we also created the Solid-State Bolt.
    The Solid-State Bolt provides a drop-in sniper bolt-action function and incorporates a VSR-type nozzle, so is only compatible with the Genesis hop unit which uses VSR hop rubbers. The SSB can easily be swapped back for a normal semi-auto bolt assembly if you want to remove the underlever and go back to semi-auto in a few minutes.

    Recommended Special Tool

    In addition to the usual selection of Allen keys and tools used for working on your KC-02, we highly recommend adding an M3 (5.5mm) wrench or driver to your arsenal for use with tightening the small M3 lock nuts on the Underlever, because if you try to do it with pliers or an adjustable spanner, you will probably scratch the anodising on your underlever parts and make it look shit, so buy one of these kind of tools to avoid that cosmetic damage:

    M3 Nut Driver - £9

    or something cheaper like this:

    M3 Nut Wrench - £3.68

    I'm sure you'll be able to find something similar in your country.

    Find us on discord if you want to know more:

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