A drilling is typically 2 shotgun barrels over a rifle caliber. Usually European and expensive. I had a Savage 12ga over 30-30 back in the 70’s. I wouldn’t mind having a 20ga over 22 or 22mag.
I once had a Tikka 12 gauge over a .243. It had a flip up rear sight with a square front and square blade. Made a nice sight picture.
One of those guns I wish I had back. The .243 even with iron sights was unusually accurate.
Long time ago I had a chance to buy a Sauer drilling in 12ga/30-06 when they weren’t hideously priced. Did get to handle one at a gun show. JMHO, it didn’t point like a shotgun nor aim like a rifle.
Drillings are masterpieces of the gunsmithing art, even so. Heard of this three barrel gun many years ago but didn’t know it was unique.