Caliber - Caliber is a kind of measurement that can describe either the level of a person’s ability or the diameter of a gun barrel. It is caliber. 
Your dad might be a high-
caliber marksman, especially when using his 22 caliber rifle.
1. the diameter of something of circular section, especially that of the inside of a tube: a pipe of three-inch caliber. 2. Ordnance. the diameter of the bore of a gun taken as a unit of measurement. 3. degree of capacity or competence; ability: a mathematician of high caliber. 4. degree of merit or excellence; quality: the high moral caliber of the era.