The tuning as described will most likely improve the rifle's firing cycle but it sounds like there are other issues.

Eliminate variables first. Is the scope securely mounted, is it focussed, are you suffering parallax error? If all ok, is the barrel lockup secure and is there any play in the breech jaws? Is the barrel clean? Have you tried different pellets?
Finally there's the fact that springers don't like being shot from a rest due to the recoil; it leads to inconsistency. Try resting on something softer like a cushion or your gloved fist on top of the rest.

HTH