Sorry I can't help you. I have also tried to find a softer spring with no luck.. I did consider taking out my stock spring and measuring the diameter and length and then trying to order a generic spring with the same diameter but shorter length to see what happens. The springs are pretty cheap online; simple compression springs. I did find a few sites that offered numerous springs; you just plugged in the parameters and it would tell you what spring you needed. Here is one site.
www.leespring.com
Let me know if you go this route.
Ben