A bore gauge is a collective term for the tools that are unique to the process of accurately measuring holes. These are a range of gauges that are used...

The gauge (in American English or more commonly referred to as bore in British English) of a firearm is a unit of measurement used to express the inner...

Wikimedia Commons has media related to .410 bore. The Shotgun Report review of the Remington 870 in 28 gauge and .410 bore The .410 Bore by Chuck Hawks...

bore — .360 in (9.1 mm) .410 bore — .410 in (10.4 mm) 32 gauge — .526 in (13.4 mm) 28 gauge — .550 in (14.0 mm) 24 gauge — .579 in (14.7 mm) 20 gauge...

The 20-gauge shotgun, also known as 20 bore, is a type of smoothbore shotgun. 20-gauge shotguns have a bore diameter of .615 in (15.6 mm), while the 12-gauge...

and gauges ranging from 5.5 mm (.22 inch) to up to 5 cm (2.0 in), though the 12-gauge (18.53 mm or 0.729 in) and 20-gauge (15.63 mm or 0.615 in) bores are...

The 8 bore (Commonwealth English), also known as the 8 gauge (American English), is an obsolete caliber used commonly in the 19th-century black-powder...

Gath, but not for the men of A.D. 1866. — Sir Samuel White Baker 4 bore Gauge (bore diameter) Holland & Holland "Stolzer & Son's Gunsmithing". Archived...

In science and engineering, a dimensional gauge or simply gauge is a device used to make measurements or to display certain dimensional information. A...

from an old English practice of bore measurements in gun-making which refers to a nominally 4-gauge bore, that is, a bore diameter that would accommodate...