Many solutions for this. It's trial and error really. Foam, rubber tubing, even heat shrink tubing around the outside of the springs. I've tried all methods and have never had any issues with tuning or springs being impeded.
One thing I also do is apply a small dab of nut sauce lubricant where the spring ends go into the blocks. I had one guitar in particular where that connection point caused a strange pinging. I do this on all of my guitars now during setups.