The recoil buffer from the Wilson Combat Shok-Buff system my work as it has a smaller diameter center hole to go over the recoil rod.
I will try to look through my "gun stuff" tonight to see if I have any left over from previous projects
By the way, I bought a second Star BM to give to my step son for his birthday. He just completed his South Carolina Concealed Weapon course. I can't think of a better budget concealed handgun other than a Kahr (way out of my price range).