The term “twist rate” refers to the rate of spin in a rifle or pistol barrel. Twist rate is measured in the number of rotations per inch of barrel length. For example, a barrel with the 1:10 twist rate means the rifling will spin the projectile one rotation in every 10-inches of barrel. Many shooters pair the ammo they use to their barrel’s twist rate—particularly in a rifle— to ensure the greatest degree of accuracy. The grain weight of the projectile is the most significant factor when matching up with barrel twist rate, but not an absolute. Generally, higher twist rate barrels can accommodate heavier projectiles for great accuracy. If the twist rate is too high on a light projectile it can cause destabilization and even disintegration of the projectile upon exit. However, when measuring the potential accuracy of any barrel, thorough testing with the widest variety of bullet types, bullet weights, and ammunition manufacturers is the only method of determining a specific rifle’s capability.