Hi Harley234.
Had this problem with another springer, told by the seller of the tuning kit to add Molybdenum grease to the spring.
I though this was bs but tried it and it reduced the muzzle energy by 3ftLbs
Initial re assembly was with 3 teaspoons of grease, cleaned two thirds of this off and now have a more damped spring action and consistent results at legal power levels. It seems a teaspoon of grease = one ftLb.
Good luck, and I would test it once in a while