The Rifled Musket, adopted by the U.S. Army in 1858, represented a significant departure from previous weapons technology. In contrast to the notoriously inaccurate and short‐ranged smoothbore musket, the rifled musket featured helical grooves running the length of the barrel that caused a bullet to spin as it left the muzzle. The spinning projectile was less susceptible to air resistance and drop, and hence had a longer, flatter trajectory. Integral to the rifled musket's design was a conoidal‐cylindrical bullet, invented by French infantry captain Claude Minié (hence the Americanized name, minie ball). When fired, the exploding powder in the rifle's breech caused a shallow concavity in the bullet's butt end to expand, grip the rifling, and create spin.

During the Civil War, both sides used rifles with close order infantry tactics designed around smoothbores, which emphasized volume of fire rather than accuracy or distance. Rifles, however, greatly increased the range at which an opponent could be brought under effective fire, and magnified the length of time spent under that fire. Consequently, casualties—and the natural power of the defense—increased dramatically. Some Civil War generals recognized the problem and began experimenting with disordered attack formations that spread soldiers out in a more open, less vulnerable configuration. Most commanders, however, persisted in traditional tactics, and disordered attacks were not accepted as official army doctrine until after the war. The rifled musket itself was the last evolutionary step in muzzle‐loaded small arms, and was quickly superseded by breech‐loading rifles that fired jacketed, metal cartridge bullets.
[See also Army, U.S.: 1866–99; Tactics, Fundamentals.]

Bibliography

Robert M. Reilly , United States Military Small Arms, 1816–1865: the Federal Firearms of the Civil War, 1970.

T. R. Brereton