Drillings?

Shotgun/Rifle Combos Over/Under are Called "Bockbüchsflinte" in German. Büchse sometimes means Tin, but with Weapons it means Rifle (with an actually Rifled Barrel). Flinte is a Shotgun, Bock means literally that one sits on Top of the Other. A Rifle/Rifle is called Doppelbüchse (usually 2 of the Same calibers) or Bergstutzen (usually with 2 Different Calibers)

Modern Drillings don't need to be a Double-Shotgun/Rifle Combo. There are plenty of Rifle/Rifle/Shotgun Drillings with different Barrel Arrangements. Nice Drillings are by Krieghoff or Blaser, but many others are available. The Blaser D99 and BD14 are pretty interesting and accurate Guns, as the Barrels aren't soldered, but adjustable.

In Germany there's an Energy Limit as well as a Caliber Limit on different Game. Deer may be taken with anything above 1000J of Energy at 100m. Boar as an Example demands a Caliber larger than 6,5mm and more than 2000J at 100m. So it's quite common to have a small Rifle Caliber (Kugel=Bullet) for Fox ord Deer, a large Caliber for Boar and Shot or Slug for Special Situations, maybe for a Fox at up to 35m or a follow up Shot with the Slug. Slug Hunting is not very common and they're somewhat unwanted by most tradition Huntsmen.

I forgot to add: Most Drillings in Shotgun/Shotgun/Rifle Arrangement don't stay like this. It's common to add a Reducing Barrel(?) or "Einstecklauf" to the Right Barrel of the Drilling to be able to use the "Stecher" Finetrigger for it. Common Calibers for the Einstecklauf are .22 Hornet, .222 Remington (with this one being effectively the smallest Deer-legal Caliber) or the Like. That's also the Way to Convert a Bockbüchsflinte (Rifle/Shotgun Over/Under) to a Bergstutzen. Large Calibers for the Bergstutzen are usually "Hochwild"-Legal, meaning they're =>6,5mm Calibre and 2000J Energy at 100m, but the smaller Calibers being Deer-Legal with 1000J of Energy at 100m.

You can't hunt everywhere in Germany. Only on a Permission (Pacht) that either you or your Jagdherr pays for. It's quite complicated sometimes. So your Gun and Equipment is mostly geared towards your Permission and Ethics. I'm not going on a Boar-Hunt with my Bockbüchsflinte. I'll take my Repeater. If I miss the Boar or just hurt it, but don't kill it, Hunting Ethics dictate that you kill the Creature as Fast and Painless as Possible.