Rifled muskets are firearms that have spiral grooves cut into their barrels, which impart a spin to the bullet as it is fired. This spin stabilizes the projectile, allowing for greater accuracy and range compared to smoothbore muskets. They became widely used during the mid-19th century, particularly in the American Civil War. One of the most famous rifled muskets is the Springfield Model 1861, which was favored by Union soldiers. The introduction of rifled muskets changed military tactics, as soldiers could engage enemies from longer distances, leading to more strategic battlefield maneuvers.