In rifles and handguns, what does the diameter of the bore usually indicate?

The diameter of the bore in rifles and handguns is referred to as the caliber. Caliber is a measurement that specifies the internal diameter of the firearm's barrel, which directly correlates to the size of the bullet that can be fired from it. For instance, a firearm described as a .22 caliber means that the bore diameter is approximately 0.22 inches.

Understanding caliber is essential for identifying the type of ammunition appropriate for a specific firearm, as each caliber is designed to accommodate bullets of matching diameters. This is fundamental in ensuring accuracy, safety, and consistent performance when handling firearms. Other options like velocity, power, and range relate to a firearm's performance characteristics but are not indicators of the bore diameter itself.