What is a common gauge designation used in shotguns?

The common gauge designation used in shotguns is referred to as a numbered gauge. In shotgun terminology, gauge is a measurement used to express the bore diameter of the barrel. The gauge number indicates how many lead balls of a certain diameter would weigh equal to one pound; for instance, a 12-gauge shotgun means that 12 lead balls of the diameter equal to the bore weigh one pound. The use of numbers (such as 12, 20, 28, etc.) is a standardized way of communicating the size of the shotgun, making it easily understood among hunters and shooters.

Terms like quarter gauge, half gauge, and standard gauge do not represent recognized measures in the context of shotgun specifications. Instead, shotgun gauges are specified using whole numbers, which helps maintain clarity and consistency across different firearm manufacturers and models.