A Drilling is a three-barrel combination gun (two shotgun barrels and a rifle barrel, vice versa, or three shotgun barrels). Most Drillings have two triggers (a very few have three triggers). The front trigger usually fires the right shotgun barrel, and the rear fires the left shotgun barrel. The rifle barrel is most often fired with the front trigger when it is selected. Most selectors are on top of the grip, but quite a few other designs can be found.
It is very important that owners familiarize themselves with a Drilling before shooting it.
The author would like to express his thanks to the German Gun Collectors Association, including members Dietrich Apel, Dick Hummel, Steve Meyer, and Hal Hamilton for helping to compile the following information on Drillings.
Most well-made Drillings in above-average condition are surprisingly accurate when using the rifle barrel(s), because of the stiffness gained with three barrels fixed together.


Normal Drilling configuration with 2 shotgun barrels over a rimmed, centerfire rifle (most are 16 ga. x 16 ga. by either 9.3x72R or 8x57JR cal.).
Two rifle barrels over a shotgun. This configuration will normally command twice the price as No. 1. German designation is "Doppelb├╝chsdrilling".
Three barrels with no two being the same gauge or caliber. This configuration is very collectible, especially if the smallest caliber is .22 LR. Again, price will be double (or more) of No. 1.
Sometimes called a Bock Drilling with one shotgun and two rifle barrels of different calibers. This variation brings a good premium over No. 1.
Rib Drilling with rifle caliber generally small (.22 LR or .22 Hornet). German designation is "Schienendrilling".
Three shotgun barrels with the same gauge or three rifle barrels with different calibers. This configuration is quite rare and healthy premiums are charged over No. 1.
A variation of No. 3, this configuration features shotgun O/U barrels with a rifle barrel on the side. German designation is "Bock-Doppelflinte mit seitlichem Kleinkaliberlauf".
Very unusual - a 3-barrel Drilling in vertical design - two rifle barrels under a shotgun barrel. This configuration is seldom encountered.