A 1:8 barrel twist rate means the rifling completes one full turn every 8 inches inside the barrel. Commonly used in AR-15 barrels chambered in .223 Remington, 5.56 NATO, and 300 Blackout, this twist rate is ideal for stabilizing a wide range of bullet weights, typically from 55 to 77 grains. It works with AR-15 barrels, upper receivers, and complete rifle or pistol builds, offering excellent versatility and accuracy for target shooting, hunting, and tactical applications.