TKS. Durr's Egg lock, I think. The large Siler or small Silers (American design) do not have waterproof pans.

Husqvarna 16 bore - right barrel is rifled 13 bore, left modified choke smooth. Both chambered for 16 bore paper, but when using brass case in the right bore, the thin brass is perfect size for 13 bore round ball - designed for farmer loading with black powder. Gun mfgr'd in 1899 or 1900.
Incidently, it's straight rifling, shot wonderfully even cylinder patterns - 70% at 25 yards with 1oz. modern shot shells. The 16 bore plastics were only 1/8" too long in the gun's 2 5/8" chambers - no pressure signs whatsoever.
Left tube shot 70% at 40 yards, even though it was mod. choked.

Typically, factory Husky ammo was available with brass case BP load for the rifled tube, paper hull with shot for the left.
They were easy to keep separate, but the shot could be used in the rifled tube as well, I assume, the reason for the straight rifling.
The also cut spiral rifling. Most of these guns known, have 20 bore rifled tube,s not 16 bore and the norm was for the left tube to be rifled, not the right.