Yes, I have a few Cast Performance bullets, they seem hard as a rock though. Within close quarters they would pass right through I think with the animal still charging, unless a head shot was present.
Absolutely nothing wrong with a pass-through.
Goin' with Sitka deer on this one.
380gr WFN copper solids and 405-420gr WFN hardcast are my choices for my six .45-70s. I do alternate 305 gr Lehigh Penetrators in the mix.
Medium velocity is recommended by most .45-70 users.