How do you untune a tuned air rifle ? I know it sounds an odd question but without cutting the spring or ordering a weaker spring, is there a way of de tuning the action.

As once the internals are polished and oil correctly i can't see any way of lowering the power.

If theres no other answer than the above then fine, just interested if theres some thoughts on how it could be done differently.

Cheers
Paul