Drilling cartridged gun, 12 gauge and rifle .30cal. A combination gun is a break-action hunting firearm that comprises at least two barrels, with at least one rifle barrel and one shotgun barrel. Combination guns using one rifle and one shotgun barrel usually are in an over and under configuration. Side-by-side versions are referred to as cape guns. A drilling refers to a combination gun that has three barrels. Four barrel combination guns, while relatively rare, have also been made.