You can still get lead wheel weights . They have a certain % tin in them and make good bullets that won't strip lead off in the barrel Modest hand gun loads . Not sure about getting lead from old car batterys . Zink and iron I don't know .
I have made zinc bullets. I had to heat the mold with a torch to get it to fill out. I have not shot any though...I just wanted to see if I could do it.
Right now I'm using straight wheel weights for bullets and they work fine. When that runs out, I have some pure lead I got from a roofer (lead flashing) and some linotype I bought off of EvilBay, and I'll need to brew up my own alloy recipe. Probably need to add a little tin solder to the mix to get the mold to fill out.