I shoot the Hornady FPBs, which are a full-bore bullet like the PowerBelt (no sabot), but a different (hollow-base) design with ballistic tip. They allegedly have a thicker jacket, and come in 2 weights, 300 and 350 gr.

I have only shot the 350 and have never failed to get a pass-through from 40-100 yds with 100 gr Pyrodex. Maybe your gun will shoot them.