Enter the bullet diameter and length into the calculator to determine the twist rate for bullet stability. This calculator can also evaluate any of the variables given the others are known.
Twist Rate Stability Formula
The following formula is used to calculate the twist rate for bullet stability.
T = (150 * D) / sqrt(L/D)
Variables:
- T is the twist rate
- D is the bullet diameter
- L is the bullet length
- sqrt is the square root function
To calculate the twist rate for bullet stability, multiply 150 by the bullet diameter. Then, divide the bullet length by the bullet diameter and take the square root of the result. Finally, divide the first result by the second result to get the twist rate.
What is a Twist Rate Stability?
Twist rate stability refers to the rotational speed or spin that a firearm’s rifling imparts on a bullet, which is crucial for its stability in flight. The twist rate is usually expressed as a ratio, such as 1:7, meaning the bullet makes one full rotation for every seven inches of barrel length. A bullet needs to be properly stabilized to maintain accuracy over distance, and different bullet lengths and weights require different twist rates for optimal performance.
How to Calculate Twist Rate Stability?
The following steps outline how to calculate the Twist Rate Stability.
- First, determine the bullet diameter (D).
- Next, determine the bullet length (L).
- Next, gather the formula from above = T = (150 * D) / sqrt(L/D).
- Finally, calculate the Twist Rate Stability (T).
- After inserting the variables and calculating the result, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
bullet diameter (D) = 0.308
bullet length (L) = 1.5
