nagel_1, the SST has a MMP 12 which is a sabot that I believe was originally designed for the Knight rifles which tend to larger bore sizes. You might try the Shock Wave which is the same bullet with the MMP-HPH 24 sabot which is designed for a .500 bore.
I have found that it works best for me to keep a number [I believe I have 7] different sizes [petal thickness] of sabots on hand and try them at home for fit before I pack to head for the range, this is easy if you take out the breach plug and push them through. Lee