A bore sighting apparatus and method includes a light source contained within a housing, which is in the form of a stepped cylindrical insert placed in the firing chamber of the firearm. The housing is in the form of a series of interconnected stepped cylindrical portions corresponding to the firing chambers of different calibers of firearms, with the largest portion being located at the rear of the firing chamber. Light is projected from the housing through the bore of the barrel and through the muzzle to a target placed at a pre-established distance from the muzzle. Calibrated points are marked on the target; and the sights of the firearm are adjusted to the calibrated points to effect the bore sighting of the firearm for a specific range.