How To Measure the Twist Rate of a Barrel

Published on September 10, 2018
Duration: 6:35

Iraqveteran8888 provides an expert-level guide on how to determine the twist rate of a rifle barrel, particularly useful for older or mystery firearms. The method involves using a cleaning rod, marker, and tape measure to calculate the distance for one full 360-degree rotation of the barrel's rifling. This information is crucial for selecting the correct projectile weight for optimal stabilization and accuracy.

Quick Summary

To measure a rifle barrel's twist rate, use a cleaning rod marked at the muzzle. Push the rod until it completes one full 360-degree rotation, mark it again, and measure the distance between marks. This distance in inches is the twist rate, vital for selecting projectiles that stabilize correctly for optimal accuracy.

Chapters

  1. 00:00Introduction: Why Measure Twist Rate
  2. 00:40Understanding Barrel Twist Basics
  3. 01:19Advanced Concepts: Gain Twist & RPM
  4. 02:26The Cleaning Rod Measurement Method
  5. 02:38Analysis: Husqvarna Model 46 (9.3x57mm)
  6. 03:49Analysis: Ruger M77 (.223 Remington)
  7. 05:17Projectile Selection Based on Twist Rate
  8. 05:37Summary and Thanks

Frequently Asked Questions

What is the easiest way to determine a rifle barrel's twist rate?

The simplest method involves using a cleaning rod, a marker, and a tape measure. Insert the rod into the muzzle, mark it at the muzzle face, push it until one full 360-degree rotation is achieved, mark it again, and then measure the distance between the two marks.

Why is knowing your barrel's twist rate important?

Knowing your barrel's twist rate is crucial for selecting the correct projectile weight. An appropriate twist rate ensures the bullet is properly stabilized in flight, leading to improved accuracy and predictable ballistics.

What are common twist rates for AR-15 barrels?

Common twist rates for AR-15 barrels include 1:9 inches, 1:8 inches, and 1:7 inches. Faster twist rates, like 1:7, are generally better suited for stabilizing heavier bullets.

Can a barrel's twist rate affect projectile selection?

Yes, the twist rate significantly impacts projectile selection. A barrel with a slower twist rate is designed for lighter bullets, while a faster twist rate can stabilize heavier bullets. Using an incompatible projectile can lead to poor accuracy and instability.

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