### Why is a 410 gun a caliber not a gauge?

The nominal bore of a .410 shotgun is.410 inch. Which is why it is properly called the .410 bore instead of the .410 gauge. In Europe it is sometimes called the 12mm, which is an inaccurate designation as a .410 bore has an actual diameter of approximately 10.4mm by metric measure. If the .410 had been named in the traditional fashion, by the number of lead balls .41 inch in diameter needed to make one…

### What all different gauge shotguns are there?

Conventional shotguns run from 10 gauge (very big) to a .410 (smallest). The most common are 12 and 20 gauges, a little less common are the 16 gauge and .410 (.410 = 67 gauge). Some of the less common gauges are 32, 28, 24, and 10 gauge. There are also monster 'punt' guns usually 6 or 8 gauge mounted to a boat. The smaller the gauge number, the bigger the gun.

### What is the relationship between a shotgun's barrel diameter and the gauge of the shotgun?

In order of biggest to smallest - 8, 10, 12, 20 bore, then .410 as the smallest. The 410 is .410 inches. Do not know the mathematical relationship between gauge and barrel diameter. <><><> The relationship is INVERSE- the smaller the number, the bigger the bore. The gauge of a gun barrel is the number of lead balls that fit the barrel that weigh 1 pound. So 12 lead balls that fit a 12 g…