Minie ball

The Minié ball, or "Minni" 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 development of the Minié ball was significant because it was the first projectile which was small enough to be easily put down the barrel of a rifled long gun. Rifling – the addition of a spiral groove inside the gun barrel, which imparted a spin to the bullet – increased the range of the gun by four times. Prior to the Minié ball, bullets had to be jammed down the rifle barrel, sometimes with a mallet, and after a small number of shots, gunpowder built up in the spiral grooves, which then had to be cleaned out. Both the American Springfield and the British Enfield rifles – the most common rifles used during the American Civil War – used the minié ball.

The Minié ball was a conical bullet with three 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.

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