Note: This post will possibly be updated from time to time. I might add some pictures. I will probably link it on the sidebar.
El Borak gave me a heads up that he was going to put me on the spot regarding bullet casting. I think that he knows that I have only been doing it for a little longer than he has, and therefore I am no kind of expert. But, I am the sort that reads a lot on the internet about things that interest me, so if I don't actually have the experience, I think I can send you to the people who do.
I got started with cast boolits* because I got started shooting revolvers. Revolvers are very versatile and very unfussy in their care and feeding. I had thought jacketed bullets were more modern and therefore superior. In some ways they are, but if you have a well made and loaded boolit, you can't improve on it much with a jacketed bullet. I've been a handloader for quite awhile. Adding another component I can make appealed to me, and hunting and shooting is my main hobby. I also have moulds for my semiauto handguns and one for .30 cal rifle. My newest addition is a mold for buckshot. I tried it out over the weekend and I got about 50% nice round buckshot. The others were out of round and small. I suspect my mold wasn't hot enough and my melt should have been hotter. I was just testing it out. I can see that it will take a lot of time to cast usable quantities of buckshot.
Lead is the primary metal used. It is actually an alloy of lead, antimony, and tin. Zinc will ruin the castibility of your alloy. Only a minute amount will ruin a lot of lead. I get my lead on ebay. I have tried to get old wheelweights at the tire shop and they had sold them to the recycler. I never tried again, as I had read that our overbearing federal govt had banned lead wheelweights. However, others are still getting them, so I need to try again. Wheelweights are in a sweet spot regarding hardness. Elmer Keith shot boolits cast from wheelweights without a gas check. There are other sources of lead, old plumbing, roof flashing, old xray shielding, etc. When I buy my lead on ebay, my boolits cost around $.05. Compared to $.20+ for jacketed, that's a pretty good deal. Obviously free is better. An added benefit is that a gun shooting boolits will never wear the barrel out. Jacketed bullets will, eventually.
Smelting is melting scrap lead, cleaning it, and mixing your alloy. This is a litlle more advanced. (that just means I have never done it, not that it is more difficult. El Borak has). Lead is heavy, so impurities float to the top. Keep your temp right, and I believe zinc wheelweights will float and can be removed. Flux the melt to mix alloyed metal back in. Then you ladle your allow into ingots to use for casting bullets. Muffin tins work good for ingot molds. Obviously they can't be used for muffins again, so don't take the Mrs's. good ones.
Casting bullets is both an art and science. It can be as simple as buying lead ingots , melting them, casting, loading, and shooting. More
advanced casters mix special alloys to achieve a desired hardness,
concoct their own lubes, and make or have made their own mould designs. The members of the Cast Boolits Forum are an invaluable resource regarding all aspects of lead boolits. There is information on sources of lead (and lead for sale), equipment, alloys, lube recipes and generally anything you need to know about casting or swaging boolits. They are good guys too. One of them, screwed by the overbearing government of California, sent me a Lee bottom pour lead pot and some lead for the cost of shipping because he can't shoot lead anymore.
There are many variations of boolits. Softer lead is used for low velocity loads, and muzzleloaders. As you increase in velocity, the hardness of the bullet should increase. The hot propellant gasses blowing past the boolit will strip lead and deposit in the barrel. This destroys accuracy and is a pain to remove**. The boolits are also lubed to keep lead from sticking to the barrel. The downside is more smoke. For the most powerful loads a gas check is used. This is a copper cup crimped on to the bullet base. Since the price of copper went north, the guys at Cast Boolits have taken to making (and selling) their own punches to make gas checks out of aluminum. There are also esoteric things like paper patched boolits*** and swaged boolits.
Boolits are a little different than what the average shooter is used to. In rifles, they top out at about 2000 feet per second velocity. Boolits can be very accurate, but they are generally less so than what we are used to with jacketed bullets. They are plenty accurate for hunting. They are not going to be useful for long range marksmanship, except perhaps the kind Matthew Quigley demostrates. There were some long range feats with bullets like this, but modern bullets are greatly superior because of their accuracy and the ability to product more streamlined shapes. You can produce small caliber boolits, say in .224" for a .223 or .22-250, but they are more difficult, to make, and not very accurate in the more cavernous cases. You can turn a .223 varmint rifle into a glorified .22 long rifle, but why? Well, because it is cheaper to shoot. Boolits tend to expand less. I have dug boolits out of a green ash log that were fairly intact, that I thought should be smashed unrecognizable. I've found shiny boolits lying on the matted grass in the spring that I had shot into the snowbanks. They were pristine except for rifling marks. I suppose they expand less because they are harder. You get the tendency to have a bigger, heavier boolit moving slower, yet hitting like a ton of bricks. Rifles might tend towards larger bores so that expansion becomes less necessary.
You will need equipment. You can start with a camp stove, a cast iron pot, a lead dipper and some Lee moulds. Or you can buy Magma Engineering automatic machines that cast hundreds per hour. I'd recommend starting with a bottom pour pot. You fill it up with lead and turn it on. Once the lead is melted, flux it to remove impurities. Put a pea sized piece of wax on top and light the vapors with a match. Stire the melt and then use a dipper to remove the slag on top. Some of the stuff that rises may be your tin that you want to keep. I recommend you do some further reading on fluxing.
Lee moulds**** are inexpensive. Cheap isn't good enough for some people. That is what use. There are higher priced cast iron molds that may bring value. You can buy six cavity moulds that cast six bullets at a time. I recommend those. They don't cost much more and there isn't anything more to learn, but you triple your production. With a new mold, you "smoke" it buy holding a candle or a match flame on the cavities. The soot is deposited and allows boolits to release freely. The procedure to cast boolits is to rest your mould on top of the pot to warm it up. You fill the cavities with lead and let the lead harden, then you cut the sprue off with the sprue cutters, open the mould, and dump the boolits out. Some quench them in ice water. Read the paragraph on safety before you try that. Any reject boolits and the sprues go back in the pot.
Next, you need to size the boolits and lube them. There are lubrisizers that do both simultaneously. I just bought Lee tumble lube molds. The boolits have small grooves. You put them in a container, squirt some Lee alox lube on them, and tumble them until coated. Dump them on some wax paper, dry them overnight and they are ready to load. Lee says sizing is not necessary as long as they chamber easily. I have never sized a boolit. More traditional boolits have deeper and wider grooves that are to be filled up with lube. Supposedly you can tumble lube these too. I do have sizers for my boolits for my semiauto .45 and 9mm. I just haven't got around to loading any of these, since the 9mm is a new acquisition and the .45acp doesn't get shot much. If you size tumble lube boolits, you lube them twice, once before you size them to keep the sizing die from leading up, and once after, in case you rub the lube off. Gas checks are also crimped on during the sizing process. The goal is to size your bullets .001" larger than the cylinder throats of your revolver. This is for accuracy and to prevent propellant gases from blowing by.
Then that is about it. Your boolits are ready to load. You do have to expand the necks of your cartridge cases so the bullets seat without shaving lead or lube off. I sometimes don't do that when loading jacketed bullets in handgun calibers. You usually don't do it in rifle calibers. So it is an extra step and an extra die you need, but most of the time it comes with the set in handgun calibers.
Cast boolits are something you think of as old technology. They are. Yet there is still innovation going on. I hadn't been to the Cast Boolits forums for quite awhile. I went back a couple months ago and got a big surprise. Someone had invented a process to eliminate lubing bullets. You simply powder coat them with acrylic powder coat. Bake it on, load and shoot. The advantages are you don't have as much smoke when you shoot, you can eliminate leading, and you don't have to taylor your hardness to your velocity. The downside is you have to have a powder coat machine, although there are some who are tumbling it on in coats. You also need an oven to bake it on. Some are using toaster ovens. I'm thinking I may go this way some day, as I don't have all the expensive lubing and sizing gear, so $60 for a powder coat machine from harbor freight and $30 for a toaster oven my be preferable than buying a lubrisizer and dies for each caliber. (Some have a complete machine for each caliber). Another downside is you have to stand all your bullets up in rows in order to coat them. It may not actually save any time over old methods (certainly not over tumble lubing). Other people are doing a similar thing with certain types of spray paint. I find it attractive because I might be able to use range scrap lead that I buy on Ebay which tends to be soft.
On safety: Leather gloves are a necessity. Lead melts at about 650 F. Your mold will get hot, the boolits coming out will be hot. You can handle the boolits for short times with leather gloves. Always cast outside, as vapors may be produced that you don't want the kids around. Lead is toxic. Wash your hands when done. I understand the worst stuff is oxidized lead that you skim off when you flux. Get rid of that. Be careful adding lead back into the pot. You don't want splashes. You do need eye protection. UNDER NO CIRCUMSTANCES ALLOW WATER TO GET IN CONTACT WITH MOLTEN LEAD. What results is a steam explosion, and hot molten lead flying around and coating everything. There are stories on the forum of guys coating their faces. Be aware that the lead you are adding to the melt may contain moisture. I guess that means be certain it does not contain moisture or don't add it. Some people recover bullets from the range and recycle them in a smelting pot. You must always completely empty the pot before adding new lead. Any water will evaporate before the lead melts. But if you simply dump it into the melt, you can get the tinsel fairy. Now perhaps you see why I look a little askance about quneching boolits in icewater as you cast them. I've never had a steam explosion, and I don't want to. One also needs to be careful with range scrap that you don't get any dud .22 shells in there. Basically, you should decide if this is something you can or should do or not.
*"boolit" is the actual technical term for cast projectiles. I may forget and type "bullet". Please forgive me.
** Fortunecookie45LC says just shoot jacket bullets occasionally to clean out the leading. I'm not sure about that, but the man has a wealth of information on Youtube about shooting and boolits.
*** Think Quigley Down Under. One my favorites.
**** for some reason I'm spelling it mould. I don't know why. Lee spells it mold.