>>63924918
minie ball doesn't flatten, it can deform but won't form a pretty disc like a musket ball, nor bloom like a modern hollow point, it'll flatten the nose a bit and tumble.
you might get fragmentation or shearing when it strikes bones, i can only find this anecdote from civilwarmed
“struck a soldier…the top of the cone flattened out, resulting in massive damage to tissue and splintering of bone”
and
"Ricocheting or flattened bullets could create even larger lacerations and could carry foreign material into the wound" which would seem to indicate prior 'roughing' from a hard surface producing better cavitation
for reference, here's some minie balls a guy collected off of a modern firing range, you can probably assume the ones with blunted noses hit the dirt, the ones that are totally shattered or flattened hit steel, but even those don't fully flatten