Maccaris spring softened my .177 HW35:
https://www.airrifleheadquarters.com...88/9689749.htm
This spring has a smaller diameter, which keeps the piston away from the piston ID.
The spring it is longer than the original, and has more preload, so it requires a well fit tight guide to remove all vibration.
( I dont like large amounts of grease for vibration dampening
)