If you want to use cast but not cast them yourself...
https://www.buffaloarms.com/reloadi...t-lead-bullets/411-459-diameter.html?p=3
I have killed deer with cast bullets in original Trapdoor carbine 45-70 and Sharps 50-70.
They do not do the job of a jacketed bullet driven at the higher speeds. The cast bullets just punch a hole through deer. A flat nose helps but nothing beats the expansion of a jacketed bullet.