Raimey is right, this is a Berger design lockwork gun on a Teschner breech action. Collath was the successor of Teschner in Frankfurt on Oder. The eagle over the crown/U proofmark visible in one photo looks slightly dissimilar to the stamps used in Suhl or Zella-M. so it may well have been proofed in Frankfurt after April 1, 1893.
while it looks outwardly similar to the Dreyse action, the Teschner is a slde-and tilt action with the barrel breeches moving upand down after sliding forward, Dreyse's was a side-swinging design with the breech ends moving sideways only.
Berger's locks are easy to recognise from the Dreyse: most obvious are the slimmer lockwork tubes, tapered down in the fence area. Unique with Berger's design are the screws in the sides of the lock tubes, that guide and stop the spring tubes. While Dreyse connected bot spring tubes with a bar, so both had to be moved at the same time, Berger's tubes are independent from each other. Berger first offered this design in the 1860s as a needle-fire, but soon it was adapted to use centerfire cartridges. As a centerfire, it was also known as a "Fuerst Pless Gewehr" = prince of Pless gun. Prince Hans-Heinrich XI of Pless was not only one of the greatest landowners in then Germany, but also an avid and well known hunter. He held the court office of master of all hunting first to the royal Prussian, after 1871 to the imperial German court. Today he is best remembered as the inventor of the German hunter's horn or bugle, called "Fuerst Pless Horn" to this day, and as composer of most of the traditional signals blown with this.
Before trying .500 3" BPE cartridges in this light rifle, please check the chambers first with a cast! Though all were called "500 Express", this caliber was once available in Germany with case lengths of 40mm, 52mm = 2", 60mm = 2-3/8", 65mm = 2-1/2", 76mm = 3" and 86mm = 3-1/4". I suspect this rifle being chambered for one of the shorter and lighter recoiling numbers.