The Minié ball, or Minie ball, is a type of muzzle-loading spin-stabilized rifle bullet named after its co-developer, Claude-Étienne Minié, inventor of the Minié rifle. It came to prominence in the Crimean War and American Civil War.
The Minié ball was a conical-cylindrical soft lead bullet, slightly smaller than the intended firearm barrel's bore, with (originally) four exterior grease-filled grooves and a conical hollow in its base. The bullet was designed by Minié with a small iron plug and a lead skirting. Its intended purpose was to expand under the pressure and obturate the barrel and increase muzzle velocity.
The precursor to the Minié ball was created in 1848 by the French Army captains Montgomery and Henri-Gustave Delvigne. Their design was made to allow rapid muzzle loading of rifles, an innovation that brought about the widespread use of the rifle rather than the smoothbore musket as a mass battlefield weapon. Delvigne had invented a ball that could expand upon ramming to fit the grooves of a rifle in 1826. The design of the ball had been proposed in 1832 as the cylindro-conoidal bullet by Captain John Norton, but had not been adopted.
The bullet could be quickly removed from the paper cartridge with the gunpowder poured down the barrel and the bullet pressed past the muzzle rifling and any detritus from prior shots. It was then rammed home with the ramrod, which ensured that the charge was packed and the hollow base was filled with powder. When fired, the expanding gas pushed forcibly on the base of the bullet, deforming it to engage the rifling. This provided spin for accuracy, a better seal for consistent velocity and longer range, and cleaning of barrel detritus.
- Sam Fadala (2006). The Complete Black Powder Handbook: The Latest Guns and Gear (5th ed.). Gun Digest Books. p. 144. Retrieved 2010-05-14.
- Robert L. O'Connell (1990). Of Arms and Men: A History of War, Weapons, and Aggression. Oxford University Press US. p. 191. Retrieved 2010-05-14.
- Brent Nosworthy (2003). The Bloody Crucible of Courage, Fighting Methods and Combat Experience of the Civil War. Carroll and Graf Publishers. ISBN 0-7867-1147-7.
- "The lead minie ball". CivilWar@Smithsonian.
- Weaponry: The Rifle-Musket and the Minié Ball- Allan W. Howey, for the Civil War Times magazine