Whether you will find the same thing true, I bought some Hornady SST's that came with a sabot and I broke a short starter trying to load them they were so tight. After that I changed sabots to a T/C Mag Express and they not only loaded much easier but the accuracy was excellent. So I am guessing who ever made the sabot on the Hornady SST made a much thicker sabot that might work for you.

When I want to shoot the SST's I now buy the Thompson Center Shockwaves.. their sabot and bullet combination works perfect for me...

You could call MMP and ask them about sabot thickness. I've personally never measured them.