Gauge was determined from the weight of a solid sphere of lead that will fit the bore of the firearm and is expressed as the multiplicative inverse of the sphere's weight as a fraction of a pound, e.g., a one-twelfth pound lead ball fits a 12-gauge bore.

Here's what you need to know about shotgun gauges, to include the differences between 10 gauge vs 12 gauge vs 20 gauge and other popular bore sizes.

A 12 gauge shotgun has a 0.725 inch bore diameter, but the “12” is calculated in a different way. The 12 refers to how many lead balls of size equal to the bore diameter (so 0.725 inches around) that it would take to weigh one pound.

Jan 31, 2020 · A 12-gauge shotgun’s bore is between 0.720″ and 0.740″ so the terms “12 bore” isn’t actually correct even though it was a common term until recently. The chamber refers to the part of your shotgun where the cartridge will sit, and the chamber size refers to the length of the fired shotgun cartridge.

Jun 16, 2022 · I’ll spoil the ending and tell you it’s the 12 gauge. The 12’s larger diameter means you can shoot whitetail with larger slugs and buckshot for more reliable kills. It offers a wider shot spread for upland birds, better patterns for waterfowl, and heavier pellets for turkeys.

Oct 18, 2024 · Ever wondered why the internal bore dimensions of 12 bore shotguns vary? These differences are not random—they play a significant role in how your shotgun performs and even how it feels to shoot. The internal bore diameter refers to the size of the barrel’s inner wall.

The internal diameter of a 12 gauge shotgun barrel is therefore equal to the diameter of a lead ball weighing 1/12 pound, which happens to be .729" (Or in British: Bore.) .410 is not really a gauge, except by convention. It is the actual diameter of the bore in decimal inches.

Feb 5, 2025 · The New World refers to 12-gauge shotguns but they are more accurately 12-bores. The term originates from muzzle-loading days, when the diameter of a number of pure lead balls making up 1lb determined the guns diameter.

Feb 17, 2024 · The term “12 gauge” refers to a shotgun that has a bore diameter of .729 inches, meaning it takes 12 lead balls of equal size to weigh one pound. Gauge does not directly correlate to the shotgun’s power or recoil but is simply a standardized measure of the shotgun’s bore size.

The cylinder bore of a shotgun is the diameter of the opening at the end of the barrel. In a 12-gauge gun, the cylinder bore is 0.730 inches. The bore sizes of other common shotgun gauges are as follows: