In the manufacture of almost all handguns, through the barrel of which a single projectile is to be fired precisely, longitudinal grooves are drawn into the interior of the barrel. These helical grooves are intended to give the projectile a twist, thus serving to stabilize the bullet trajectory, and are referred to as rifling. The surfaces located between the rifling grooves, which are rotated along the length of the barrel, are referred to as fields.

Since the field diameter inside the barrel is always slightly smaller than the rifling diameter, the rifling caliber is correspondingly larger than the field caliber and corresponds to the actual diameter of the bullet. This causes the bullet to be slightly compressed in the barrel. This creates characteristic scratch patterns for the respective barrel.