Steps to casting:

Wheel weights make fine bullets for most applications. Issues with cast bullets center mainly around hardness. Wheel weights have some antimony added for hardness. Reason for hardness is to be able to drive the bullet at faster speeds. Softer bullets will leave lead deposits in barrel. If you are shooting at 9mm or less velocity soft leading in the barrelis not usually a problem. DO NOT try to use old car batteries, main problem is that the lead has arsenic added for hardness.Also problems with getting rid of acid and getting the tough case apart.

DO NOT add pieces of lead that has ANY moisture on it to already melted lead. Water will turn instantly to steam and cause an explosion of melted lead with possible burns to skin and eyes. Wear eye protection anyway. It is all right to put damp lead in cold pot to start with, as the gradual heating will dry out the lead long before it melts.

Have some type of lead pot. I used an iron frying pan at first, but recommend and electric pot such as the Lee. Read instructions. After lead is melted stir in some wax which will give off fumes which you light with a match. This is called fluxing and helps bring the waste to the top. You should get a kitchen table spoon for this(not wife's kitchenware, get your own). Use spoon to scoop off dross( waste material, dirt, etc) which will float to the top. Everything is lighter than lead so all will float. In the case the wheel weights, you can scoop off the steel clips first, before any fluxing.
When lead looks clean you can start casting.

For the best speed for the money I recommend a 2 cavity mold, but use what you have. The first 2 or 3 bullets should be put aside to be remelted since the mould will cast misshapen bullets until it warms up. Have a wooden stick to knock open the mould latch and a cloth pad to drop the bullets on. A way to get additional hardness is to quench the bullets immediately in water. It takes only a few seconds for the bullets in the mould to cool enough to be dropped from the mould.

Reccommend you the Lyman cast bullet handbook, but the lyman reloading manual has a section on bullet casting.

I would do all this in a well ventilated place, preferably out side with a slight breeze to carry the fumes away. Don't let anyone distract you while working.

Shooting bullets in rifles at higher velocities: You need gas check bullets. Gas checks are little copper cups of the appropriate caliber which allow the bullet to be fired fast without leading the barrel. There is an upper limit to how fast lead bullets can be driven. They found this out after smokless powder was invented. As the bullet is fired faster, it starts to melt and lose accuracy. About 2000 fps, IMO and IME, is the upper limit for reasonable accuracy. If it is fired fast enough it melts in the air and you see a line of blue smoke, thus the expression from earlier days "going like a blue streak". Accuracy is better around 1500 fps and I was told that best accuracy was about 1300 fps.

Waste that you scoop out has small amounts of lead in it and probably is supposed to be disposed of in some certain way. Considering the amount of more dangerous stuff that is put in land fills and the fact that the greedy land fill companies are ever anxious to put the things near settled areas and streams that supply water to someone downstream, I don't see why putting this minute amount of stuff out for garbage pick up wouldn 't be ok, but I'll probably get flamed for that. In this area their is adequate recycling provision anyway.

Have fun.

Haynk