30-caliber magnums, in terms of their best-recognized muzzle velocities with a 200-grain bullet. Note: Listed muzzle velocities were the fastest listed for a 200-grain bullet in the Nosler #9 ...

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.