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Rocky’s Reloading Room |
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Cast Bullet Thoughts
I’m a big fan of cast bullets. Call it getting back to basics, call it being cheap, or call it call it using the best bullet for the job. All three descriptions fit nicely.
In handguns, a cast bullet is the right bullet for the job most of the time. Only when muzzle velocities get above 1500 feet per second, or when bullet expansion is needed is a jacketed bullet a better choice for the handloader. (We’re not discussing personal defense loads here, because those should always be factory-loaded.)
In rifles, cast bullets provide great off-season practice, non-destructive small game rounds, ideal training loads and even nostalgic big game performance.
Cast bullets are easier on the gun, generally give higher velocity at a given chamber pressure, and deliver ideal performance on targets, whether game or paper. Did I mention cheaper? Even commercially cast bullets are four or five times cheaper than jacketed. Self-cast bullets can be almost free, at least for the materials.
Lead bullets can be obtained, as mentioned above, either from commercial sources or from the fruits of one’s own labor. Commercial bullets have the advantage of being ready to load, highly uniform, inexpensive and readily available, especially in handgun styles. Disadvantages are limited selection of bullet styles or weights, no selection of bullet hardness (more on that later), and high freight charges if bullets must be ordered and shipped.
Self-cast bullets can be made in almost any weight, shape or caliber, from nearly any imaginable lead alloy, and at almost no cost except time. Casters do need a lead-melting furnace, a sizer/lubricator press and a selection of moulds for each type of bullet to be made, but all of these are quickly amortized in savings. Lead and other metal ingredients can be obtained from many sources at little or no cost, or even from commercial sources. Moulds and handles are available in thousands of calibers, bullet styles and weights for virtually every cartridge ever made. Even the most obsolete rarity can be made to bark again with self-cast bullets. There are even custom mould makers who can create a bullet mould to your own design should you wish to do so for whatever reason.
(By the way, mould is the correct spelling for the shaped metal blocks used to cast bullets. Properly speaking, a mold is what comes out of a mould. A cast statue is a mold, for example, while the shell in which it was made is a mould. We won’t refer to that green stuff on your old bread!)
While I’ve dabbled in casting my own bullets, I prefer to simply buy commercially made lead bullets for the majority of my shooting. In my case, it’s both a matter of time and consistency. When I test loads for handguns, my results should be reproducible. If I shot bullets that I’ve cast, it would be difficult or impossible for others to get similar results. There’s also the matter of time. I’d rather have the extra hours to reload, go to the range or write. I also have to earn a living, as my wife gently reminds me.
Only when a particular cast bullet is not readily available will I fire up my furnace and create some. Several years ago, I was doing some of the earliest reloading experiments with the 9mm Makarov pistol, for example. There simply were no bullets available for this recently-imported caliber. The round doesn’t use the standard 9mm bullet (.364” rather than the usual .355”) and no US maker was yet producing either cast or jacketed bullets. RCBS kindly sent me their prototype dies and a bullet mould and sizer for the article I was writing. The mould dropped a 95-grain roundnose that needed no sizing. I used a liquid lube and loaded them as-cast for perfect results. I still have a hundred or so of them, but I suspect that my mould will stay cold for a long time. There are now commercial cast as well as jacketed bullets for the Mak.
Similarly, I buy the cast bullets I shoot in my rifles. Both 30-caliber and 7mm are easily found. If I wanted to shoot cast bullets in other calibers, I’d have to make my own, but I have little need for cast bullets in smallbore calibers that are normally used for varmints.
Loading Basics
Powder selection for cast bullets can be surprising. Generally, faster-burning powders are best. The rapid pressure buildup allows a cast bullet to obturate in the bore. That means that the bullet actually gets shorter and fatter due to its own momentum and malleability. The rear of the bullet actually starts to move before the front gets going, and the result is that the bullet swells up and fits the bore better. A slower-burning powder may not achieve this result. A slower powder also exposes the rear of the bullet to hot gasses for slightly longer, which can melt the base of the bullet. That’s not good, as you might guess.
In handguns, traditional powders work fine, because those rounds were designed around cast bullets. The surprise comes with rifle cartridges, where very fast shotgun and pistol powders work great with cast bullets. All these powders are designed to bulk up well, ignite easily and burn cleanly. Where rifle powders are called for, choices like 4198 are ideal. Again, they are bulky and ignite easily.
Spherical powders are almost universally a poor choice for cast loads in rifles. They take up very little space and they can be heavily deterred, which makes ignition iffy. The combination of excess air space and poor ignition can result in blooper loads, hangfires or even extremely high pressures. None are good, so stick to flake or extruded-type powders only for cast bullet loads, especially in rifle cartridges.
A word here is in order about fillers. In years past it was fairly common for reloaders to insert paper wads, various cereal grains or synthetic fluff into the cartridge case between the powder and the bullet. The idea was to take up the airspace with an inert substance, and keep the powder near the primer. Better ignition was the thought. However, there have been a number of instances of bulged chambers and other nasty happenings attributed to the use of fillers. At best, some powder can migrate around or through such fillers and never burn. At worst, fillers can serve as a bore obstruction. With today’s much hotter primers and easily ignited, bulky, flake powders, I’ve never found a need for fillers of any kind. Use them if you choose, but I choose not.
My experience is that mild primers work best with cast bullet loads. I’ve read of a few loads where magnum or hot primers gave good results, but I’ve never been disappointed with standard strength primers. Try those first, unless a specific recipe calls for something else.
Case preparation for cast bullets loads is standard, with one small exception, which I’ll get to in a bit. You can elect to full-length, partial or neck size. Whichever way you like is fine. Trimming to uniform length is important if you crimp. You may wish to tumble or clean cases a bit more than normal between loadings, because cast bullet loads can result in slightly smoked cases at times. Beyond that, there’s nothing special. The exception comes after sizing and before bullet seating. Every case neck needs to be smoothly and evenly inside chamfered to avoid damaging the soft lead bullets during seating. Even better is to expand or slightly bell the case mouth. Most handgun dies include a mouth expander plug either as part of the decapper or separately. Few rifle die sets include a case mouth expander. However, the good folks at Lyman make a great gizmo called an “M” die. This die has a two-step expander inside. The first step expands the case neck to just smaller than a cast bullet to insure a uniform but firm grip. The second step expands a very short section of the neck to just over the diameter of the bullet. That short section allows you to insert a cast bullet easily, straight and without damage. If you intend to load many cast bullets in rifle cartridges, by all means invest in the proper diameter M die.
Finally, there’s the matter of crimp. Cast loads for rifles are usually pretty low in recoil, and the bullet shanks are long with plenty of grip. Lever-action cartridges should be crimped lightly, not to keep pullets from pulling out from recoil, but from being driven deeper into the case from magazine spring pressure coupled with recoil. Semi-auto pistol cartridges also tend to get jammed deeper into their cases, but this time it is due to the round getting slammed into the fixed feed ramp as the bolt slams shut. These also need a crimp.
Revolver loads are different. Here, recoil can be quite sharp, and bullet mass is high. Bullets can easily be pulled out of their cases a bit and protrude from the front of the cylinder. The bullet will then jam the action. So revolver rounds need a good firm roll crimp. There’s almost always a crimp groove properly located for this. Adjust your seating die per directions. Semi-auto pistol dies have a taper crimp design instead of a roll crimp. The crimp is less noticeable, but die adjustment per instructions will result in perfect rounds here, too.
So far, the loading techniques have applied to any cast bullet, whether homemade or commercial. Let’s now look at a few specifics for casting your own bullets.
Casting Basics
OK, let’s assume you’ve decided to delve into this bullet casting business. The very first thing I recommend you do is to get a copy of the Lyman Cast Bullet Handbook or the similar book from RCBS. Casting bullets can either be dead simple or amazingly technical. The more you get into it, the more technical you can get. In that regard, it’s much like reloading itself. Even a raw beginner can turn out safe, usable and acceptable loads. But it’s also possible to get very involved with all kinds of minutiae and details in the attempt to produce ever better products.
There are also a few mandatory safety aspects of bullet casting, all of which are correctly addressed and emphasized in the manuals mentioned. Among the safety tips are the need to always wear protective eyewear AND bodywear. Heavy gloves, long sleeves, shop apron and closed shoes are necessary. Even a tiny drop of molten lead splashed down your shirtfront or inside your slip-on moccasins will make you a believer, trust me. Molten lead also puts out poisonous fumes that can be inhaled. Good ventilation is a must, and a fan that directs fumes away from you is even better. It wouldn’t be a bad idea to get an annual blood test for lead if you cast regularly. I’ve never heard of a private caster developing lead poisoning, but prevention is better than the alternative.
Casting starts with the selection of a mould. Bullet moulds are available from a number of makers, with Lee, Lyman, Redding/Saeco and RCBS being well known. Lee moulds are made of aircraft aluminum and the rest are steel. Both work well. The aluminum moulds achieve casting heat faster and drop bullets very cleanly, but are easy to damage. Steel moulds sometimes take a number of bullets to come up to temperature before they drop usable bullets, and must be protected from rust between uses, then thoroughly degreased before use.
Pointed bullets may look good, but you’ll find that they are harder to cast well, and are often less accurate as well. Blunt-nosed cast bullets are best. Roundnose or flatpoint designs in either rifle or handgun should be your first choice. Also pick a bullet that’s heavy for your caliber. For a 30-caliber rifle, for example, select a 170 to 200-grain cast bullet design. Most handgun cartridges are optimized for cast bullets, so traditional bullet weights are good. In the 44, a 240 to 250-grain bullet is perfect, for example. With cast bullets, think slow and heavy for best results.
With a mould and the proper handles on hand, it’s time to find bullet metal. Millions of perfectly adequate bullets have been cast from mixed or unknown batches of scrap lead. Good sources of acceptable alloy include wheelweights, range scrap, electrical cable sheathing, plumbing supplies, metal recyclers and other sources. A great casting alloy used to be plentiful from printing shops and newspaper printers. But modern printing systems no longer use hot type, so linotype and other such alloys are a thing of the past.
Most tire shops sell their used wheelweights to metal recyclers on contract, but you may be able to talk a friendly owner into a few pounds now and then. I pick up used bullets at my local range whenever I walk to and from the target butts. On weekdays, I can often have an hour or so with no other shooters there. In that time, I can scrounge ten or more pounds of spent lead bullets just off the ground! What better source of bullet metal than bullets?
Pure lead is no good for bullets, except muzzleloaders, where it is the only good choice. All other bullets must be made of an alloy. Small amounts of tin help the molten metal flow and mold better. Tin allows the bottoms of lube grooves and sharp edges on the bullet to be true and sharp, not soft and rounded. It also helps harden the alloy a bit, but not much. Most scrap lead already contains some tin, especially wheelweights. Another good source is plumber’s solder or even electrical solder.
The hardening alloy is antimony. Just a few percent of antimony can double or triple a bullet’s hardness. All commercially cast bullets are very, very hard. Spent bullets are therefore a good source of antimony to sweeten an alloy of otherwise unknown scrap. You can also buy pure tin and antimony, but they can be difficult to proportion and melt in their pure state.
Almost all other metals are bad for bullet alloy. Among the worst are aluminum and zinc. The presence of either one will ruin your alloy for bullet casting. If you simply can’t get good bullets from a particular batch of alloy, suspect contamination. Use that batch for fishing weights, padded vise jaws or doorstops. Aluminum and zinc contamination can come from several sources, with the most likely being scrap aluminum foil and wheelweights (unfortunately). Examine all scrap wheelweights you intend to melt, and discard any that don’t look or feel right. Zinc weights are large for their weight, and are shinier than most used lead. Wheelweights with the standard steel rim clips are probably OK, but any tape-on weights should be viewed with suspicion.
While I’m on the topic of contaminated lead, the one source of scrap lead that should NEVER be used for bullets is salvaged lead-acid batteries. The lead plates from batteries are contaminated with calcium, sulfur, copper and other nasty things. Handling the plates may result in acid burns and melting them can produce clouds of acid vapor. Just forget it.
The other thing that should never get into a melting pot is water. The smallest drop of water in molten lead will result in a veritable Vesuvius of molten metal in your face. If you wash scrap bullets or wheelweights, be sure to let them dry for at least several days before you use them. It’s best to add washed scrap to an empty pot first, before you add heat. That way, any residual water can be driven off before the lead melts. If you ever drop a damp piece of scrap into an already molten pot, believe me, you will never forget the result when that water flashes explosively into steam. It may be the last thing you ever see, in fact.
There are many other aspects of how to cast good bullets, but they are fully covered in both the Lyman and RCBS manuals. Another great source of knowledge is the Cast Bullet Association, an organization devoted to bullet casting and shooting cast bullets. I can’t improve on their expertise.
Leading in Barrels
The major objection to shooting lead bullets is that they can cause leading in a gun barrel. Leading is simply part of a lead bullet that has melted and attached itself to the interior of the bore. Several things may cause bullet melting. We’ve already mentioned powder gasses melting the bullet base. That can be corrected with a different powder, lighter powder charge or protecting the bullet base with a gas check. Suffice it to say that a gun bore already fouled with very hard jacketed bullet debris will act like a rasp to soft lead bullets. Never switch between jacketed and lead bullets without thoroughly cleaning the bore to bare steel first.
Leading can also be caused by insufficient or incorrect bullet lubrication. Which lube and how much to use is addressed in the manuals above, but any of the modern lubes applied correctly will generally prevent leading at all but extreme bullet velocities.
Probably the two biggest causes of barrel leading are incorrectly sized bullets and bullets of incorrect hardness. Let’s look at sizing first. Lead bullets generally perform best, in all respects, when they are the same diameter or slightly larger than the gun’s groove-to-groove diameter. In a 30-caliber rifle, the groove diameter is usually about .308” diameter. A bullet for that bore should be sized to .308 - .310” diameter for best accuracy and minimal leading. One to two thousandths of an inch over groove diameter is a safe rule of thumb for almost all situations. (There may be exceptions for some revolver rounds, but that’s due to cylinder, not bore dimensions.) Bullets smaller than groove diameter are almost always a disaster. Hot gas will leak past the bullet by way of the rifling grooves, and that hot, focused gas will almost always melt the sides of the bullet. Gross leading and nonexistent accuracy are the results.
The other major cause of leading is bullets of the wrong hardness. The temptation here is to think, “Harder is better” but that is NOT valid. For most handgun use and even some rifle use, most commercial cast bullets are actually too hard. A quick way to determine if a cast bullet is too hard or too soft is to see where in the bore the leading starts. If the bore is clean from breech until somewhere near the muzzle, the bullet is probably too soft (or the lube is wrong). The increasing velocity of the bullet is the cause of the melting when the leading starts near the muzzle. A harder bullet (or correct lube) will easily fix that problem.
But if the leading starts near the breech and ends part way down the bore, the problem is that the bullet is too hard (or too small). The culprit here is hot powder gas. A bullet too hard or too small will not seal the bore. As discussed above, that results in bullets melting down their sides and depositing a coat of solder in the bore. The leading stops because the escaping gas cools rapidly by contact with the bore, and due to expansion. The cure is to size the bullet larger, use a softer bullet or both.
Can we predict how hard or soft to make a bullet to start with? Yes there is. I did not discover the formula to be presented, nor can I now discover just who did, but a very experienced bullet caster developed it. The method is simply to divide the average maximum chamber pressure for a given load by 1,422 to get the correct Brinell Hardness Number (BRN) for a lead bullet. BRN is a method of determining the hardness of a lead alloy, similar to the Rockwell scale for steel and harder metals. On the Brinell scale, pure lead has a hardness of five, standard bullet alloy about 10, Lyman #2 alloy or wheelweights are about 15 and Linotype about 22.
Let’s look at an example. The 38 Special, 44 Special and 45 Colt all operate at standardized maximum chamber pressures of about 13,000 psi (also measured in a different system called copper units of pressure, or c.u.p. which is not the same, but the difference here is immaterial). Divide that pressure by 1,422 (1,400 is close enough) and the result is just over nine. An alloy of 16 parts lead to one part tin and no antimony scales about 10 BRN. That’s a pretty soft bullet, and nowhere near the BRN 20+ of most commercial cast bullets!
To need a bullet of BRN 20 would require a chamber pressure of more than 30,000 psi. That’s well into near-maximum pressures for the 357, 41 or 44 magnums. Unless such a hard bullet is a very good fit in the bore, some bore leading near the breech is almost a certainty. Yet, most shooters who buy commercial cast bullets cry for ever-harder bullets when they detect leading. The commercial casters know better, but shooters THINK they know best and won’t buy bullets that are softer – and would shoot better.
Knowing the proper BRN for a bullet to be used in a given cartridge may be the easy part. Achieving that BRN can be tricky. The good news is that it’s not necessary to be very precise with the BRN. Straight wheelweights, as mentioned, scale about BRN 15, which is close enough for most any load short of full magnum levels. The manuals will give you the approximate BRN for a variety of alloy mixes, or will tell you how to formulate an alloy to achieve a desired BRN. You can also purchase a bullet hardness tester that can check and alloy or a bullet if you want to be really precise. There are also techniques to harden bullets that end up cast too soft, but that goes beyond the scope of this article.
Once again, rifle bullets are a bit different. Here, a bullet can be driven well above the velocity possible in a handgun, so you might need a fairly hard bullet to control leading. The bummer is that a hard bullet at high velocity can actually shatter when it hits big game bones. The solution here is to use a slightly softer bullet that will stay together on impact, but size it correctly and protect the base with a gas check. Gas checks are tiny cups of copper or aluminum that are applied to a special reduced-diameter step at the rear of the bullet (almost like a boattail section) either before or during bullet sizing. Some types just press on and some are crimped in place. Both work fine, but the bullet mould must be one designed for a gas check to have that short base section. A few commercial bullets come with gas checks applied, but they’re more expensive due to the labor of individually applying each gas check. Plinking and practice bullets can be shot plain-based.
As I wrote near the beginning of this piece, I use cast bullets for at least 90% of my handgun loads. I shoot jacketed bullets for about 90% of my rifle loads, and the rest are cast. I seldom cast my own any more, and so I’m not a real expert at casting bullets per se. But, I shoot a goodly number of lead bullets both at paper and afield. So I do know a little bit about loading and shooting cast bullets. I know that cast lead bullets are easy to load, cheap to shoot and meet every demand I have of them. Reasons enough to stick with them.
And, one of these days, I’m going to find a nice clean little Savage 340 bolt gun in 30-30 chambering, or maybe a Krag carbine in 30-40, and I’m going to buy that gun. I’ll put a fat peep sight on it, and shoot nothing but cast bullets through it. I think it’ll be a hoot.
Rocky Raab
Ps: I found that gun! It’s a nice clean Savage 340 in 30-30. I bought a peep sight for it, and the fun is about to begin. I’ll be reporting on it as time goes by. Stay tuned! |