What Is a Bullet Jacket?

Eduard Rubin and the Jacketed Bullet

• In the early 1880s, Eduard Rubin designed the first copper-jacketed bullets for the Swiss Army. Previously, bullets had been made of pure lead, which was ideal for black-powder weapons. Lead is heavy, making it hard-hitting, and soft, causing it to expand on impact, which increased their damage to soft tissue. As scientists developed more powerful propellants they discovered that pure lead bullets melt at the higher firing velocities now possible. This deforms the lead bullet, affecting accuracy and leaving lead deposits on the inside of the rifle barrel.

  Rubin solved this problem by inventing the bullet jacket: a thin laminate of copper that surrounded the lead bullet. Because copper is harder than lead, it withstands higher velocities without melting or losing its shape. At the same time, the lead core keeps the bullet heavy and inexpensive to manufacture.

Modern Bullet Jackets

• Rubin's jacketed bullet transformed small arms which were able to shoot higher-powered bullets with greater range and velocity than previously thought possible. His jacketed bullet proved such an excellent technology that bullets similar to his design continue to be used by all of the armed forces in the world.

  Modern bullet jackets are usually made of copper alloys, which are easier to cold-work than is pure copper. Some copper jackets are nickel-plated for a chrome finish. Chinese and some European arms manufacturers use steel jackets. More exotic jacket materials, such as Teflon, are sometimes used.

Full-Metal Jacket

• Rubin's original bullet, and the bullets now used by nearly all the world's military organizations, are full-metal jacket bullets. This means that the bullet jacket, usually made of copper, completely covers the sides and point of the lead bullet. The base of the bullet is not jacketed. The familiar cone-shaped bullets for the M-16 and for the AK-47 are full-metal jacket bullets.

  Full-metal jacket bullets are used by all the major military organizations of the world because the Hague Convention of 1899 bans the military use of bullets which "expand or flatten easily in the human body." The full jacket keeps the bullet in one piece and prevents expansion on impact, making these bullets acceptable for military use.

Soft Point

• Soft-point or hollow-point bullets are not used for military purposes but are the bullet of choice for law enforcement and hunting purposes. A soft-point bullet has a jacket on the sides, but the nose is left unjacketed, with the lead exposed. This allows the bullet to expand on impact, causing much greater tissue damage to a living target. Soft point bullets have an exposed flat or rounded nose. Hollow-point bullets have a depression in the lead nose, which allows greater deformation and expansion.

Total-Metal Jacket

• Total-metal-jacket bullets have a jacket on the nose, sides and base of the bullet, compared with the full-metal jacket that leaves the base exposed. The total jacket prevents the lead from being vaporized or expelled during firing. This keeps lead pollution to a minimum. For this reason, total-metal-jacket bullets are often used in firing ranges and in competitive shooting events.