HW100 Anti-Tamper Removal

On early models of the HW100 the power parts were separate components but on later “Anti-Tamper” models the hammer, shuttle and power adjuster are assembled as a unit, power is adjusted at the factory and the adjuster is then snapped off, making further adjustment impossible. The problem is that power can still vary, up or down, as the rifle beds in leaving the owner with no way to compensate.

You can buy Anti-Tamper removal kits, which essentially convert the rifle back to pre Anti-Tamper spec, but you still need to remove the factory Anti-Tamper in the first place and if you can do that then you don't need a kit because you can adjust the power with the Anti-tamper still in place, albeit no longer operational, and with the added benefit that the rifle still looks original.

Below are are links to two excellent stripdown and reassembly videos. They both also contain instructions for Anti-Tamper removal, however I believe that I've found an even easier method.

HW100 Disassembly and anti tamper removal

HW100 POWER up/down ANTI TAMPER REMOVAL

Warning: This is not a guide or a recommendation. I am not a qualified gunsmith and this is simply a description of what I did. I accept no liability for any adverse consequences that may result should you choose to copy this method.

But let's get to it. The Anatomy of the HW100 Anti-tamper:

What's needed is to remove the (hollow) adjuster from the shuttle. However, the adjuster won't be sticking out like it is above: It'll have been snapped off flush with the end of the shuttle and it's remains held in with an aggressive thread-lock. The first step is to remove the grub screws (there may be one in either or both holes). Next we need to find a way to clamp the shuttle without damaging it. I made vee blocks from wood which could be clamped around the front half of the shuttle in a vice, leaving the threaded section sticking out.

I then heated the threaded section with a blow torch for about 30 seconds until the thread lock gave up. At that point, I jammed an appropriately sized flat bladed screwdriver into the adjuster and turned it clockwise until it screwed out. Success looks like this:

At this point it's basically done. I used paint thinners and a wire brush to clean the remains of the thread lock from the adjuster and then polished the heat discolouration off the shuttle. Then I screwed both parts back together and, without the thread-lock, I can quite easily turn the adjuster with a screwdriver to set whatever power I need and then lock it in place with the grub screws. In time I may replace the thread lock on the adjuster, but for now the job's a good 'un!