It depends on what you are casting for? Casting lead bullets is done by the pressures you want to achieve. Pouring straight WW alloy can handle most handgun pressures developing up to 1,200 fps. A small amount of tin added to the pot will allow for a better pour and mold fill. Pure lead runs a BHN of 5 to 6 which is hard measure with a simple Brenell tester. Pure lead is fine for light loads. A BHN above 12 to 22 can handle a velocity of 2,000 fps when hard lubed and gas checked.
If you plan on just throwing everything in the pot, who knows what you will get. Make sure you flux it to save the tin.