How hard is to hard for roundballs ? and best way to check hardness
homestyle?? any input would help me out..i know there are some home casters out there..

It really is not a question of how hard, but what is the best quality lead you can find? When I was young, I cast a lot of ball out of wheel weights and never thought anything of it. Now I try to cast pure lead only. But that is getting hard to find. But if all I could lay my hands on was wheel weights, then I would be shooting wheel weights.

so what about killing power ? pure vs wheel weight ? and expansion,

Expansion of course with the wheel weight will be less. Penetration will be greater though. As for killing power, you are putting a 1/2 inch hole through the vital organs of an animal. Putting a 1/2 inch hole through a heart is not something anyone would want. I think shot placement will be the same as with any projectile. Put it where you should and let the wound do the rest of the things.