Ive got the old style of adjuster on mine and at some point in its life, someone has used a longer screw to hold the grip mount. This has made a groove at the front of the velocity adjuster screw.
This was discovered when johnnyboy very kindly spent a couple of hours doing a full strip down and street of my gun a few weeks back.
I thought id use this to my advantage, I've just put a small m5 grub screw up through the hole so it sticks out just enough to stop the velocity screw being turned, while taking care not to touch the spring.
The velocity screw moves about 5mm either way now.
Ive used a slightly shorter grip mount screw so it doesn't touch the grub screw and may paint the grub screw black so its harder to see if its being tampered with.
Ive got a spare velocity screw on order and am going to go to an engineering firm to see if they can make a longer one so it bottoms out and stops the power being turned up.
I was looking at cutting the spring down a bit so the screw would bottom out at about the right power but not sure it will work.