Wisconsin Hunter's Safety Practice Exam

Caliber refers to the specific size and shape of the barrel of a firearm, measured in inches or millimeters. This affects the size of the cartridge and bullet that the firearm can properly use. Option A is incorrect because it refers to a safety feature, not the definition of caliber. Option B is incorrect because a scope is an optic attachment and not related to the size of a firearm. Option C is incorrect because while rifling does play a role in the accuracy and distance of a bullet, it is not the overall definition of caliber.