Encyclopedia · Identification, collecting, and safety

Measuring caliber and projectile diameter

Measuring the bore of a gun or the diameter of a projectile establishes its caliber, a first step in identifying and matching guns and their ammunition.

Also known as: measuring caliber.

PurposeEstablish caliber to identify guns and projectiles
MethodMeasure bore diameter or projectile diameter accurately
UseMatching a projectile to the gun that fired it

Getting the caliber right

Caliber, the diameter of the bore, is one of the first things established in identifying a gun or projectile. Measuring the bore of a cannon, or the diameter of a shot or shell across its widest bearing surface, places it among the known calibers.

An accurate measurement is essential, since projectiles were made slightly under bore diameter and calibers were often close together, so a careful reading distinguishes, for example, a 3-inch from a 3.67-inch projectile.

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Sources & further reading

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