Quote Originally Posted by lensman57 View Post
The problem with getting a third party regulator work efficiently with S400/500 is more to do with the removal of that bloody cap on top of the grub screw that adjusts the power externally. Unless one knows how to tackle the problem there is every chance that the valve block will be damaged. It is possible to leave it alone ( much safer from a legal point of view ) but then the full benefits of the regulator will not be had. The consistency will be there for sure but achieving the required efficiency to increase the shot count will be not be there.

A.G
As you say it's a waste of time trying to reg an Air Arms without removing the anti tamper. I used a mill to do my 400 and HFT so it could be drilled spot on and wouldn't attempt it any other way to avoid other damage. Adjusters removed and blanked off so everything is altered by spring and hammer settings so other than completely stripping it down and swopping parts you can't alter the power. The only way power can raise is through temperature and being set at 11.3 fpe it should still stay below, or if the reg fails letting more air through which would show on the gauge.