A friend and I got a very good deal on a couple of PBS-4 suppressors for our AKs. But, much to our dismay, when they arrived from Hong Kong they turned out to be VFC PSB-4s, and as such had 24mm barrel threads rather than the usual 14mm threads.

Rather than going to all the hassle of packing them back up and returning them to Hong Kong, I did a quick search and found a UK supplier who had a 24mm to 14mm AK thread adaptor. This seemed the easiest remedy, particularly as the supplier didn't have any replacement 14mm type PBS-4s in at the time.

Above: The beautiful VFC (GB Tech) PBS-4 suppressor, for the AK74U, along side the Razor Workz 24mm to 14mm AK barrel thread adaptor.

However, when the adaptor arrived our cunning plans were once again thwarted, as it turned out that the adaptors were slightly too long to fit the VFC suppressor. The adaptor stuck out from the back!

The problem was that there was a thin metal collar or lip just inside the suppressor that stopped the adaptor from screwing in all the way. Not wanting then to have to send all the items back, I decided to take some drastic action and somehow remove the offending lip by means of my handy Dremmel tool.

THE MODIFICATION

Note: Please ensure you wear proper safety goggle for doing this. The minute particles of metal that the cutter trims off get everywhere, and are very sharp.

This was my very first attempt at any sort of airsoft 'modding', and although not very complex the thought of actually cutting away a piece of alloy - and the consequences of any mishaps - was a bit scary. Luckily my trusty Dremmel had just the tool for the job, a tungsten carbide cutter.

Above: Picture 1 shows just how much of the thread adaptor protruded from the suppressor collar. A small lip (Pic 2) prevented the adapter from screwing in all the way. In the background you can see my Dremmel Multitool with the tungsten carbide bit attached.

 I carefully started grinding down the inner-collar with my Dremmel - at a three-quarter speed. Gently trimming slithers of alloy off a little bit at a time, until the collar was flush with the inner thread. Great care had to be taken with this operation, as the tungsten carbide cutter went through the suppressors alloy like a hot knife through butter.

After enlarging the hole for the adapter, I tidied up any metal 'flash' using a Swiss file (Pic 3). I also sprayed the inside of the suppressor with black paint where VFC had done a very bad job of coating (I'm picky like that). I also touched up a couple of scratches (told you you have to be VERY careful with the tungsten cutter!).

Above: Picture 3 shows the inside of the suppressor collar after trimming, with the adaptor now able to screw through and sit flush with the outer collar (Pic 4).

I then cleaned out the suppressor, taking care to get rid of any minute flecks of metal, that might cause the adaptor to stick when screwed in. Be careful at this point, as the bits of trimmed metal can be very sharp and stick to your fingers. I vacuumed my work top thoroughly after the job, cleaned my Dremmel and washed my hands to get rid of any stray chips of alloy.

I then reassembled the PSB-4.

And here we have the finished ensemble! My lovely little Kalash AK74U and the VFC PBS-4 suppressor...

Note on the 24mm to 14mm AK thread adaptors:  These adaptors are fairly common - and cheap - items in the USA, where imported AKs are modified to take the standard Western 14mm muzzle thread. Unfortunately, they are not so common in the UK, where the AK47 is a banned firearm.

Only one UK supplier - I could find - had these adaptors, this was Razor Workz. I have mentioned this company before, they are a very high quality manufacturer of airgun/airsoft accessories - such as silencers - milled to the highest specification. As such, they are a little pricey - the brass adaptor I bought was £27 (+PP)!

I would have opted to order the adaptor from the USA - where a lower quality alloy version can be got for just $17 - but there seems to be a blanket ban on exporting even the most innocuous 'gun' accessories from the USA to the UK.