The bore of a gun relates to the diameter of the hole in the barrel - and in turn the diameter of the bullet the gun can fire.
Caliber "Caliber" is a word for the diameter of the bullet or the bore of the gun.
bore diameter
The TIGHTEST choke (which is smallest) is the Extra Full. The largest (no choke at all) is known as a cylinder bore.
The bore is the inside of the barrel- that is, the hole that the bullet is fired through. The diameter of the bore is measuring how wide the bore is from one side to another.
It depends on the caliber of the bullet.
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 bore is the inside diameter of the barrel. Simply put, it's the hole down the middle of the barrel.
By measuring the inner diameter of the barrel across the lands.
Bore diameters vary from gun to gun due to wear reduction of the boring tools and to accurately find he bore diameter you must "Slug the barrel". In most cases, it is safe to use bullets of the same diameter as those used by the factory when making ammunition.
The range is not directly related to bore diameter. And the largest gun over built (The Tsar bombard) has a 36" bore.
Diameter of either the cartridge or the bore, dependent on how the measurements are taken.