starmetal,
the thing that really stands out is 150 gr bullet 15-17 grs 2400=1637-1843 FPS.
180 gr bullet 19-21 grs 2400=1303-1435 fps. Losing 300-400 FPS doesn't make sense. a 115 gr bullet with 15.9-17.9 grs 2400=1870-2088 fps.
I know T/C's have lots of freebore but I also question this load. I have 14 different T/C barrels but none of the Herretts. I would be really cautious using this load. It may well be a misprint. Mark