.410ga. being smallest 20,16,12,10ga. being biggest
In the interest of ensuring that the information this new shooter recieves is accurate, I would like to point out that there is no such thing as a 410 gauge shotgun. It is accurately called a .410 caliber bore, as the ".410" refers to the bore diameter (caliber), NOT the gauge. The term "gauge" in reference to shotguns refers to the number of solid lead balls of that bore diameter required to equal one pound. For example, a 12 gauge shotgun is such because 12 lead roundballs of bore diameter equal one pound, 20 balls for a 20 gauge, 28 balls for a 28 gauge, etc.... The bore diameter (caliber) of a 12 gauge is roughly .72 cal.
Mike