Gun Digest Contributor Phil Massaro takes us through the basics of understanding barrel twist rate.
What is twist rate, and why is it important in selecting the right bullet and rifle for your intended purpose?
- Twist rate is the ratio of how tight the rifling spirals are in your barrel.
- Twist rates are expressed by a ratio that starts with 1 (1:7, 1:10, 1:14, etc.).
- Tighter, faster twist rates are needed to stabilize longer, heavier bullets.
- When a longer bullet encounters a slow twist rate, it becomes unstable.
- This affects the trajectory and the way the bullet impacts the target.
Most shooters, even those relatively new to the sport, have heard of or are familiar with “twist rate” in some way, even if it's just by looking at the ratio stamped onto a rifle's barrel. However, if you intend to get the most out of your rifle, it's something you need to know and understand.
In the video above, Gun Digest Contributor Phil Massaro explains the basics of twist rate. In short, he says, twist rate is a ratio describing how tight the spirals, or rifling, are in your rifle's barrel.
This is important because some twist rates, especially those referred to as “slow” or “slower” — which translates to fewer rotations before the bullet exits the barrel — don't provide enough rotation to properly stabilize longer, heavier bullets. A lot of great varmint guns feature a barrel with a relatively slow twist rate because the bullets being used are very lightweight, and that twist rate adequately stabilizes them by spinning them faster.
Bullets intended for use on larger game for serious long-range accuracy are generally heavier and longer. The reason longer bullets are used for shooting at longer ranges is because they are sleeker and generally offer an improved ballistic coefficient — they are more aerodynamic and less prone to wind interference and atmospheric drag.
Of course, the use of these longer, heavier bullets requires a tighter, faster twist rate that can properly stabilize them in flight. Otherwise, you end up with a bullet that does not fly properly and which might be inaccurate or hit the target incorrectly (sideways, for example).
Check out the video above to get the straight scoop from Massaro. And be sure that you're keeping twist rate in mind when selecting your rifle and bullet combination.
Authored by ballistics expert and worldwide hunter Philip Massaro, the Big Book of Ballistics covers the minutia of interior, exterior and terminal ballistics in plain, graspable language. From ignition in the cartridge to dynamics down the bore to the bullet blasting out a target, Massaro unravels exactly what happens after the trigger is pulled. Get Your Copy Now