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.
The roofing lead and sinkers are pure lead, soft and not very useful for bullets as is. The soft lead is nice for specialty stuff like shotgun slugs and muzzle loader bullets if tin is added to mae a 20/1 Lead/Tin alloy
Wheel weights are a good base product for bullets. Add some tin (2-4%) and most handgun uses are satisfied. Add some antimony from a source like Linotype and you can do pretty much anything. I cast my high velocity bullets for .30 and .224 rifles from half WW and half linotype. Crimp on a gas check and 2800 fps is perfectly reasonable.
Oh my....I better do some research. I was thinking about for a .40 handgun. I am no sharp shooter. I am mostly do shotgun sports but also have a .40 SW I was thinking about reloading for. I don't even know what some of the acronyms stand for....I need some school'n!