How Bullets Are Made

How bullets are made
The two most common bullet-forming methods are casting and swaging. Hollow points can be formed by either method. Hard (harder than lead) solid bullets can be stamped (a metal punch cuts a bullet-shaped piece out of a bar or sheet of softer metal) and machined from metal stock. Machining includes any process where a machine is used to shape metal by cutting away portions. A typical machine used for bullets is a lathe. A lathe rotates the bullet metal against steel chisels to gradually cut away material.

CASTING A BULLET
Casting is pouring molten metal into a mold. This mold is hinged and when closed has a hollow space that is the shape of the bullet. The metal is melted in a crucible (a metal or ceramic pot that can hold molten metal safely) and then poured into the mold.
After the metal has cooled, the mold is opened and the bullet falls or is knocked out. Any imperfections are removed by cutting or filing. If the bullet is extremely deformed, it can be melted down and the process repeated.
To cast a bullet with multiple sections of different materials, the first material is poured into the mold to partially fill it. After this material has cooled and partially or completely solidified, the second molten material is poured into the mold to fill it partially or completely. This can be done several times, but most often is done twice to create a bullet with a heavier section (for penetration) behind a softer section (for expansion).

SWAGING A BULLET
1 Swaging is a cold forming process, which means that it involves shaping metal without heating to soften or melt it. The appropriate amount of material to be swaged (measured in grains) is placed in a die. A die is a harder metal container with a cavity (an empty space) shaped like the bullet without the back end. The die is part of a larger stationary object or is held in place on a platform.
2 A metal punch that fits into the open end of the die is forced into the die to the appropriate depth. As the punch forces the bullet metal into the die cavity, the material takes the shape of the cavity. The pressure can come from a manual or hydraulic press, from repeated hammer blows, or from a threaded punch that is screwed on. Excess metal is squeezed out of bleed holes.
3 The punch is removed from the die and the bullet is pushed or pulled out of the cavity. Any imperfections are removed by cutting or filing.
4 Multiple swaging steps can be used to insert partitions, to create a bullet out of multiple materials, and to further define the shape of the bullet. Sometimes several steps are necessary to add features such as a hollow point.
The bullet jacket
Some bullets have jackets of harder metal surrounding a softer core.
5 A coin-shaped piece of jacket metal is punched out of a strip or a sheet. The punch is usually a round metal cylinder that is pushed through the jacket material into a depression in a table. Some punches are rounded so that the piece of metal is shaped like a cup. Sometimes, tubing is used instead of a coin or a cup of metal.
6 If the jacket material is too hard to be formed easily, it can be annealed. Annealing is heating the metal, often with a gas flame, to soften it and make it more workable.
7 The jacket material is then placed in a die or over a punch and the punch is forced into the die. There may be several different punches and dies used to form specific features in the jacket. One of usual steps is to make sure that jacket is of uniform thickness. The thickness is typically 0.03-0.07 in (0.08-0.17 cm). Some bullets have a thin jacket electroplated onto the core.
Bullet assembly
8 Jackets and multiple bullet parts can be joined by methods such as swaging them together, casting one section on top of another, soldering, gluing, or electrical welding. Soldering is a process of joining two pieces of metal together with solder, an alloy that is usually tin and lead. The solder is melted and sticks to both pieces of metal, gluing them together after it cools and solidifies. Glues for joining multi-part bullets are usually epoxies, plastics that are formed from two different fluids that harden when combined. The epoxy fluids are dispensed from tubes and mixed, then the pieces are joined together and held in place until the epoxy hardens. Electrical welding is the process of passing a strong electrical current through two metal parts that are in contact so that they soften and stick together. If the joining method is not strong enough, the bullet may fall apart prematurely.
9 Next, grooves may be cut or pressed into the shank of the bullet. The grooves can be pressed into a soft bullet by rotating the bullet against a ridge on a metal wheel, or they can be cut into the bullet on a lathe. Many cast bullets already have grooves.
10 The bullet is sometimes coated with a I O lubricant, usually wax, oil, or moly, which reduces bore fouling from soft bullets. Jacketed and hard bullets are not generally lubricated, though they can be, especially with moly. Bullets are often degreased (put in a solvent bath to remove grease from previous manufacturing steps) before the lubricant is applied.
11 Wax and oil lubricants can be applied by rubbing with a soft material such as a cloth wheel, spraying, pouring, or dipping. Moly is applied by placing bullets in a container of moly powder and rotating the container so that the bullet and the moly particles tumble around until the bullet is coated.
12 The completed bullets are then manually removed and packaged.
Source : www.madehow.com