Driving band

In an artillery shell, the driving band or rotating band is a band of soft metal near the shell's bottom, often made of gilding metal,[1] copper, or lead. When the shell is fired, the pressure of the propellant swages the metal into the rifling of the barrel and forms a seal; this seal prevents the gases from blowing past the shell, and engages the barrel's rifling to spin-stabilize the shell.

Russian 122 mm shrapnel shell, which has been fired, showing rifling marks on the copper driving band around its base and the steel bourrelet nearer the front

The shell is stabilized for yaw in the barrel by a smaller bourrelet band near the front of the projectile. This band keeps the projectile travelling straight in the bore, but doesn't engage the rifling.

As shell weight increases, it becomes more difficult to engineer a driving band that prevents propellant gases from either blowing past it, or blowing it off the shell.

Some weapons that operate at high rates of fire, such as the GAU-8 Avenger Gatling cannon, use plastic driving bands instead of soft metal. Using plastic as a swage material reduces wear on the barrel's rifling, and extends the life and average accuracy of the weapon.

In a small-arms rifle, the entire bullet is typically covered in copper or another soft alloy, making the entire bullet its own driving band.