The Teschner-collath guns used "Blitzschlosse" = trigger plate locks almost exclusively. These are cocked by a pushrod linked to the long, Lefaucheux-type underlever under the foreend. Collath drillings have three locks, one for each barrel. But Collath had his own ideas how a drilling should work and his own, patented barrel selector system: Collath drillings have the safety on the tang like the usual shotgun, first the wingnut type shown above, later the common slide. The barrel selector is a small lever on the right, lower edge of the frame, above the forward bow of the triggerguard. When this lever is up/flush to the frame, both triggers are linked to the shotgun locks. When down, one trigger, the one with the set adjustment screw, is linked to the rifle barrel. And here is another quirk: Collath apparently believed that the Rear/left trigger is better suited to the rifle barrel, so many of his drillings are set up this way.
Fluid barrel steel came into use quite early: since 1865 the Prussian army used it exclusively, first on Dreyse needlerifles. It was made by several steelworks/companies, such as Witten, Roechling, Baildon, Poldi. Krupp was a relative latecomer in this market, as they had concentrated on artillery before, but the "name" coming from their famous big guns soon made it famous and widely used.