Rifled muzzle loaders are firearms that have a rifled barrel, meaning the inside of the barrel has spiral grooves. These grooves help to spin the projectile, improving accuracy and range compared to smoothbore firearms. They are loaded from the muzzle, or front end, which is where the term "muzzle loader" comes from. These weapons were commonly used in the 19th century, especially during the American Civil War. The introduction of rifled muzzle loaders marked a significant advancement in firearm technology, allowing for more precise shooting and greater effectiveness on the battlefield.