0.729 inches or 18.5 mm
The nominal bore size of a 12-gauge shotgun refers to the diameter of the shotgun's barrel, which is approximately 0.729 inches (18.5 mm). The "gauge" system measures the number of lead balls of the bore diameter that can fit into a pound; thus, a 12-gauge shotgun is designed to accommodate 12 lead balls of that diameter. This measurement influences the shotgun's performance, including its shot pattern and recoil.
This is a shotgun with an internal barrel diameter (called the "bore) of approximately .410" which shoots a shell which is about .410" in diameter. It is the only shotgun shell size that uses this convention. A 12 gauge shotgun, for example, does not have a bore of "12". A 20 gauge shotgun has a smaller bore than a 12 gauge and a 10 gauge has a bigger bore than a 12. Gauge size is based on the number of lead balls of the bore diameter which are required to make a pound (16 ounces). 10 balls, 12 balls, or 20 balls.
A 12-gauge shotgun refers to the diameter of the shotgun bore, with the gauge system indicating the number of lead balls of the bore's diameter that would weigh one pound. In a 12-gauge, it takes 12 lead balls of the same diameter to equal one pound. The bore diameter of a 12-gauge shotgun is approximately 0.729 inches (18.5 mm). This gauge is one of the most popular sizes for shotguns, commonly used for hunting and sport shooting.
Think of a lead ball which is the diameter of the inside of the barrel of the shotgun. The gauge of the shotgun is the number of balls that size to make up one pound. 12 balls - 12 gauge 20 balls - 20 gauge 28 balls - 28 gauge Exception - .410 bore is the actual bore diameter
Shotguns are named according to the number of bore-diameter-sized lead balls that can be made from one pound of lead. For example, a "12-bore" shotgun means that 12 lead balls of bore diameter can be made from one pound of lead. The larger the number, the smaller the bore diameter.
The bore is the inside of the barrel of the gun. Bore dimension for most rifles is caliber, which is the bore diameter in fractions of an inch or in millimeters. Some older big game rifles had designations such as "12 bore", which is bore diameter the size of a shotgun barrel of the same gauge. Gauge is the number of round balls fitting the bore that can be made from a pound of lead.
A shotguns gauge is a measure related to the diameter of the smooth shotgun bore and the size of the shotshell designed for that bore. Gauge or diameter of the bore is determined by the diameter of 1 lead pellet times the number of pellets required to equal 1 pound. ex. 12 gauge is equal to the diameter of 1 of the 12 lead balls that equals 1 pound. ex. 20 gauge is equal to the diameter of 1 of 20 lead balls that equals 1 pound. ex. 3 gauge is equal to the diameter of 1 of the 3 lead balls that equals one pound. The larger number of gauge the smaller the bore.
A 20-gauge refers to the size of a shotgun, indicating the diameter of the shotgun bore. The gauge number is inversely related to the size of the bore; specifically, a 20-gauge shotgun has a bore diameter of .615 inches and is smaller than larger gauges like 12-gauge. The 20-gauge is popular for its balance of manageable recoil and effective performance, making it suitable for various hunting and shooting activities.
It is determined by the number of lead balls of the same diameter as the barrel bore needed to make one pound. e.g. 12 lead balls of .735" diameter weigh one pound - therefore the shotgun with that bore size is called a 12 gauge.
The term 12 gauge is used to describe the caliber(bore diameter)of your shotgun.A 12 gauge barrel is 72 caliber,but the word gauge is used so people can determine you are talking about a shotgun,instead of a rifle.
I suppose you mean: What is a 30 caliber bore? The bore of a Rifle is referred to as the caliber, which equates to the diameter of the bullet it fired. A gun that shoots a 9mm bullet would be a 9mm caliber or the bore size. Most guns originally made in US were measured in INCHES. Thus a 22 caliber rifle was a gun that shot a 0.22 inch diameter bore. Since the US Army began to change over to the metric system, it began making guns to the 9mm and 7.62mm sizes. Some bores can have alternate names. A new pistol bullet is the 0.40 INCH caliber designed by Smith&Wesson is also referred to as the 10mm caliber. The bore size of Shotguns are measured using Gauge. For example, shotguns are referred to as 12-Gauge or 20-Gauge. Gauge is an unusual measurement. The gauge equates to the number of lead balls that are made to the diameter of shotgun's bore and totals a weight of 1 pound. Thus, a 12-gauge shotgun has a diameter that of a ball that would weight 1/12 of a pound. That means the Larger the bore of the shotgun, the smaller the gage number. A 12-gauge shotgun is bigger bore than a 20-gauge shotgun.
Yes, it is larger, the smaller the gauge the larger the bore i.e. 3 gauge is larger in diameter than a 8 gauge or a 12 gauge.