Heavy Metal The How–And Why–Of Bullet Casting

Story and photos by Steve Johnson

All the equipment that you need for safely casting bullets. From left: Safety Glasses, heavy leather gloves, melting pot, mold, stick for cutting sprue, slag container and heavy stainless steel tea spoon for skimming slag.

Casting bullets is a very simple process, but like anything involving the shooting sports, there are some important details requiring your close attention. Since very early in the history of firearms, lead has been the projectile material of choice for a couple of reasons. First, lead is heavy and dense; second, lead melts at approximately 625 degrees Fahrenheit—which means it can be melted in a campfire. This made it possible for early hunters, trappers and trailblazers to carry bullet molds for their guns and cast their own bullets in the field. Modern times have brought some real advances in bullet casting, from melting pots to molds to specialized alloys for different types of shooting. Here’s how these innovations come together to make it possible to cast your own bullets.

Examples of Single Cavity (top) and Double Cavity (bottom) molds.

There are two basic types of melting pots on the market. Though they both operate with electric heat, the first style has an open top and designed to be used with a ladle. The second style incorporates a valve into the melting pot so the molten lead can be poured directly from pot into mold.

Molds all work on the same basic principle: Two halves form a precise cavity that is the shape of the projectile to be formed. Generally it works best to heat up the mold before beginning the casting process. This allows the lead to stay molten for a moment while it is inside the mold, which is important because it gives air bubbles a chance to escape, and the lead to form a solid bullet without any imperfections. Imperfections are usually the result of too little or too much heat in the process. A mold and/or lead that’s too cold will create lines or even air pockets in the bullet. These imperfections can cause the bullet to fly inconsistently and inaccurately. Too much heat in the process will cause the bullets to have a “frosted” appearance. (Some believe these bullets should be re-melted, but I haven’t seen any adverse effects on performance or accuracy.) It’s generally better to have more heat than less when casting bullets; 750–800 degrees Fahrenheit is a good place to start.

When the lead is poured into the mold, pour a little extra on top, this is called the sprue. When the sprue cutting plate is tapped open with the stick, it will trim the sprue neatly and cleanly from the base of the bullet.

Once the bullets are cast, they need to have lubricant applied to their outer surface to reduce fouling in the barrel when they are fired. There are a few ways to accomplish this. First (and simplest) is liquid lubricant, like Rooster Labs’ Rooster Jacket or Lee’s Liquid Alox. Both can be easily tumbled onto the bullets. Once that’s done, you’ll set the bullets on their base to dry—and your bullets are ready to load into cartridges. When using lubricants like these, it’s important to cast bullets to within .001 of an inch of the diameter barrel that they will be fired in; e.g., don’t use bullets over .309 inches in a .308-inch barrel—and the closer to .308 inches the better. Other bullet molds are designed to cast bullets that are a couple thousandths of an inch oversized, which then must be run through a special tool called a “lube sizer.” The lube sizer forces the bullet through a sizing die and applies a firm, waxy lube that’s forced into the sizing chamber. The lube sizer can also be used to install a “gas check.” Gas checks are designed protect the base of the bullets during loading and firing. The base of the bullet is very critical to accuracy. Gas checks also prevent the lead on the base of the bullet from vaporizing during firing.

The result of all the hard work is a good looking Keith style wadcutter that's ready for the range.

Home-cast bullets are great for any type of shooting, from target practice to dangerous-game hunting. There are a variety of different alloys that range from pure soft lead to lead/linotype alloys. The Brinell scale is used to define the hardness of lead, soft lead rates around 7 and linotype is around 20. Soft bullets will foul more and work better at lower velocities; harder bullets work better at higher velocities and foul very little, especially when combined with a high-quality lube. In hunting situations, the lower the Brinell rating, the more ductile the bullet. (Ductility means it can be shaped without losing its toughness.) The more ductile the bullet, the more rapidly it will expand when it strikes game. That’s great for slower-moving bullets on small and medium game. But if you are chasing bigger, tougher game, you’ll want to use a harder, tougher bullet traveling at a higher velocity. Automotive wheel weights come in around 12 on the Brinell scale and make great bullets that work well for a variety of applications from target practice to hunting. Casting bullets is a simple, enjoyable pastime that can be very fulfilling for both beginner and experienced shooters. It is a great hobby that can last a lifetime, and save one heck of a lot of money over the years.