Here is a pic from Corneli's book of the Collath needle fire cartridges with their integral, nail-shaped needles.

If a whole gun is signed "C.Berger & Comp.", it probably is pre-1873, but the Witten steelworks may have used the well established Berger name even longer. As Berger and later Witten supplied the trade not only with barrel blanks, but according to Ziesing also with action forgings such as revolver frames, I now believe they supplied Teschner, Collath and others with the rough parts for the slide-and-tilt actions and not the other way around. This would explain some Collath-looking guns from northern Germany, with completely different lockwork inside, fi a gun in a friend's collection with coil-spring-striker locks. Kief of Peine even held a safety patent for Collath-type guns. He blocked the big V-mainsprings of the trigger-plate locks.