The higher pressures and temperatures produced by smokeless propellants were more than plain lead could support. This was overcome by adding an outer skin of harder metal to lead bullets. Since pure copper is difficult to cold-work, copper alloys became the standard jacket material.

What is the purpose of copper jacketed bullet?

A bullet jacket generally allows for higher muzzle velocities than bare lead without depositing significant amounts of metal in the bore. It also prevents damage to bores from steel or armor-piercing core materials.

What is the advantage of copper plated bullets?

A1: A lead bullet is very soft and would fly apart. The copper coating is harder and will resist the stress of the firing and the velocity during flight and also not be totally smashed upon impact.