How do You Measure Caliber?

The caliber is the measurement of the inside of a rifle barrel. For instance, a 22 gauge is 22/100 of an inch in diameter. For a shot gun, the gauge is an indirect measurement – the gauge number is the number of lead balls it would take to make up one pound of lead. A 16 gauge shot gun shoots lead balls that weigh a pound if you have 16 of them. For more information, look here: