In 2015, I decided to neck the 6.5 Creedmoor case down to 0.257-caliber ... the Sporting Arms and Ammunition Manufactuerer’s Institute (SAAMI) has approved the 25 Creedmoor, and Hornady has ...

The most common definition of “caliber,” as it pertains to guns, is about as straightforward as you could want it to be: Caliber simply mean the diameter of the hole in a rifle or pistol barrel.