What Is My Gun Number & How Do I Use It?

Published on July 26, 2025
Duration: 5:49

This video introduces the 'Gun Number' method for rapid wind drift estimation in long-range shooting. Derived from the first digit of a projectile's G1 Ballistic Coefficient, the Gun Number directly correlates to mil radian wind holds for specific wind speeds and distances. The technique offers a faster field guesstimate compared to complex calculations, supplementing formal wind mastery courses.

Quick Summary

The 'Gun Number' is a rapid wind calling technique derived from the first digit of a projectile's G1 Ballistic Coefficient. For example, a G1 BC of 0.610 gives a Gun Number of 6. This number corresponds to a full value wind of 6 mph causing approximately 0.6 mil drift at 600 yards, simplifying on-the-fly estimations.

Chapters

  1. 00:01Introduction & Bonus Content
  2. 00:18What is a Gun Number?
  3. 00:23Coltac Product Mention
  4. 00:37Defining the Gun Number Method
  5. 00:56G1 Ballistic Coefficient & Gun Number
  6. 01:18Example: 6.5 Creedmoor Gun Number
  7. 01:58Gun Number 6 Explained (6 mph wind, 600 yards)
  8. 02:20Wind Direction & Barrel Twist
  9. 02:49Wind Drift Estimation by Yardage
  10. 03:23Adjusting for Different Wind Speeds
  11. 03:41Advanced Example: Angled Wind Call
  12. 04:31Cosine Value for Angled Winds
  13. 04:49Comparison with Ballistics App
  14. 05:14Benefits of the Gun Number Method
  15. 05:20Q&A and Community

Frequently Asked Questions

What is the 'Gun Number' in shooting?

The 'Gun Number' is a simplified wind calling method where the first digit of your projectile's G1 Ballistic Coefficient becomes your Gun Number. This number directly relates to mil radian wind holds for specific wind speeds and distances, offering a quick field estimation.

How do I calculate my Gun Number?

To calculate your Gun Number, simply take the first digit of your bullet's G1 Ballistic Coefficient. For instance, if your bullet has a G1 BC of 0.610, your Gun Number is 6.

How does the Gun Number relate to wind drift?

A Gun Number of 'X' means that a full value wind of 'X' miles per hour will cause approximately 'X/10' mil drift at 600 yards. This method allows for rapid estimation of wind holds at various distances.

Can the Gun Number method be used for angled winds?

Yes, the Gun Number method can be adapted for angled winds. After calculating the full value drift, you subtract the cosine value of the wind's angle relative to your line of fire to get an adjusted wind call.

What are the limitations of the Gun Number method?

The Gun Number method is most accurate for estimating wind drift out to about 900 yards. Beyond that, factors like gravity and projectile BC degradation become more significant, requiring an adjustment of adding an extra tenth of a mil to the hold.

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