A general service normally does the trick....
Take it apart, degrease, deburr & polish(fine grade of emery cloth) any working parts to make them smoother, new piston seal, LIGHTLY regrease the working parts using the recommended greases WITHOUT getting any in front of the piston seal as this will cause dieselling, and then do what Tony(phantom) said, felt/rubber between the action and the stock to lessen vibration and you should have yourself a quiet smooth working rifle
Darryl