https://www.youtube.com/watch?list=PLUoRcFYUnOPD0ba8dmKNPRAMtIEqrhRVZ&v=B2WCpXgGM50

https://www.rockislandauction.com/detail/70/2377

"Manufactured between 1907 and 1925, the heart of the arm is a Mauser bolt action receiver and buttstock, with the rifle barrel outfitted with a ramp bead front sight, a two leaf rear sight, "crown/N" and "172/28" on the lower left chamber flat, and a contoured rib addressed "DEUTSCHE WAFFENFABRIK, GEORG KNAAK, BERLIN S.W. 48". On the underside, connected with a hinged barrel band at the muzzle and a lightly engraved casehardened frame at the rear, is a single shotgun barrel, which swings to the right for loading via a horn under lever, with a small manual extractor and a checkered forearm. The receiver is casehardened and lightly engraved, with "2,67g G.B.P./m.g." on the left side, textured receiver rings, and a scene of two doe on the floor plate. The checkered long spur shotgun hammer is tucked into the left side of the upper tang, partially covered by the rifle safety, and inside the guard are two triggers, one single set rifle trigger in front and a standard shotgun trigger in back. The checkered pistol grip stock is grooved on the right side to ease shell loading, with a black plastic grip cap, raised cheekpiece, an engraved trapdoor on the underside covering an empty compartment, and a serrated buttplate. Shotgun barrel measurements: Bore diameter at 9 inches from breech: .660, wall thickness at 9 inches: 0.10, muzzle constriction: approximately .02 (modified). Stock measurements: Length of pull is 13 inches from the shotgun trigger, with a drop of 1 3/8 inches at the front of the comb, 1 1/8 at the rear of the comb, and 2 1/4 inches at the heel. Overall weight: 9 pounds 15.6 ounces."