How Many? A Dictionary of Units of Measurement
© Russ Rowlett and the University of North Carolina at Chapel Hill

Table of Contents
About the Dictionary
Using the Dictionary

Shotgun Bore Diameters

Most of this data was taken from the World Almanac and Book of Facts 1996; a reader contributed the data for 24-, 28-, and 32-gauge.

Gauge 

Bore diameter
(millimeters)

Bore diameter
(inches)

6

23.3

0.92

10

19.7

0.77

12

18.5

0.73

14

17.6

0.69

16

16.8

0.66

20

15.6

0.615
24
14.7
0.58
28
14.0
0.55
32
13.4
0.526

Notes:

  • In some cases it is customary to state the diameter directly in inches: a ".410 gauge" shotgun, more properly called .410 bore, has a bore diameter of 0.41 inch. This measurement is really the caliber rather than a gauge.
  • The gauge number is intended to be the number of lead balls per pound, the balls being of a size that will just fit into the barrel.

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You are welcome to email the author (rowlett@email.unc.edu) with comments and suggestions.

All material in this folder is copyright © 2003 by Russ Rowlett and the University of North Carolina at Chapel Hill. Permission is granted for personal use and for use by individual teachers in conducting their own classes. All other rights reserved. You are welcome to make links to this page, but please do not copy the contents of any page in this folder to another site. The material at this site will be updated from time to time.

February 4, 2003