Gauges and bores
Why is .410 referred to as a bore, but other shotguns are gauges?
The .410 is the actual diameter of a .410 bore. A gauge is measured by the amount of lead balls of the corresponding bore diameter that will equal one pound. For example, 28- gauge is the diameter of a lead ball that weighs 1/28-pound. Twenty-gauge is the diameter of a lead ball weighing 1/20 pound, and 12-gauge is the diameter of a lead ball weighing 1/12 pound.
The 16-gauge is often called the perfect gauge because a 16-gauge lead ball weighs 1/16 ounce. A proportional dimensions of a 1-ounce, 16-gauge load are ballistically ideal.
Sports on 01/14/2018