Twist Rate is the rate in which a bullet spins as it travels through a barrel. This twist plays a significant role in stabilizing a bullet as it leaves a barrel and travels to its target.
Twist rate is indicated by the length (in inches) it takes a barrel’s rifling to spin a bullet one complete revolution. For example, a barrel with a 1:8 twist rate will spin a bullet one revolution for every 8 inches that it travels through the barrel. The smaller the second number (inches) in a twist rate, the faster the twist.
It should be noted that a bullet’s weight and length factors in to how it performs when leaving a gun barrel with a specific twist rate.