rifled

Rifled refers to a firearm barrel or bore that contains spiral grooves cut or pressed into its interior surface. The grooves generate lands that grip the projectile, causing it to spin as it moves down the barrel. This spin stabilization improves aerodynamic stability, accuracy, and effective range compared with smoothbore designs of the same caliber.

Rifling is described by the twist rate, the number of inches of bore per full turn of the rifling, such as 1:10 or 1:7. A faster twist stabilizes longer, heavier projectiles, while a slower twist suits shorter bullets. Rifling profiles vary, including conventional land-and-groove, polygonal rifling, and micro-groove designs. Barrels are produced by methods such as cutting, button rifling, hammer forging, or broaching. The choice of profile and twist rate depends on cartridge type, desired accuracy, and firearm purpose.

Historically, rifling emerged in Europe during the 15th–16th centuries and became widely adopted in the 19th century with breech-loading rifles and metallic cartridges, transforming accuracy and military tactics. Rifled artillery and specialized rifles also developed in the 19th century, expanding the use of spin-stabilized projectiles beyond small arms.

Maintenance and variation: rifled bores require regular cleaning to remove copper fouling and other residue, as fouling or improper maintenance can degrade accuracy. In addition to rifles, some shotguns use rifled barrels for firing rifled slugs, though most shotguns remain smoothbore for other types of ammunition.