What EXACTLY is a Gauge?

Published on October 7, 2025
Duration: 1:29

This video explains the concept of shotgun gauge, a historical measurement system used to define bore diameter. It clarifies that gauge is an inverse measurement, where a smaller gauge number indicates a larger bore diameter. The video also highlights the 410 bore as an exception, being a caliber measurement rather than a gauge.

Quick Summary

A shotgun gauge is a historical measurement system for the internal diameter of a shotgun barrel, determined by the number of solid lead balls of the barrel's diameter that equal one pound. It's an inverse system: a smaller gauge number signifies a larger bore diameter. The 410 bore is an exception, measured as a caliber (0.410 inches).

Chapters

  1. 00:01Introduction to Gauge
  2. 00:14Defining Gauge
  3. 00:23Historical Origin of Gauge
  4. 00:31How Gauge is Measured
  5. 00:47Inverse Relationship of Gauge
  6. 00:56Common Gauge Sizes
  7. 01:01The 410 Bore Exception
  8. 01:10410 Bore vs. Gauge
  9. 01:23Enduring Terminology

Frequently Asked Questions

What is a shotgun gauge?

A shotgun gauge is a historical measurement system for the internal diameter of a shotgun barrel. It's determined by the number of solid lead balls of the barrel's diameter that equal one pound. For example, 12 lead balls of a 12 gauge barrel's diameter would weigh one pound.

Is gauge the same as caliber?

No, gauge and caliber are different. Gauge is primarily used for shotguns and is an inverse measurement system. Caliber, typically used for rifles and pistols, is a direct measurement of the bore diameter in inches or millimeters. The 410 bore is an exception, being a caliber measurement.

How does shotgun gauge work?

Shotgun gauge is an inverse system: a smaller gauge number means a larger bore diameter. So, a 10 gauge shotgun has a larger bore than a 12 gauge shotgun, and a 20 gauge has a smaller bore than a 12 gauge.

What is the 410 bore?

The 410 bore is an exception to the gauge system and is technically a caliber. Its bore diameter is approximately 0.410 inches, which is less than half an inch. Unlike other shotguns measured by gauge, the 410 is defined by its direct bore measurement.

Related News

All News →

More General Videos You Might Like

More from GUNBROS

View all →