This is an extremely rare Mauser experimental/prototype, pistol "Serial Number 1", chambered in the powerful .45 ACP cartridge. This design was originally started in 1909, in 9 mm Parabellum with a few very early test samples proving unsuccessful. However Mauser continued to improve the design through 1911, wherein the Mauser factory applied for a patent, which was approved in 1912. It is estimated that only 150-200 of the 9 mm Parabellum designs were actually produced with the highest recorded serial number (in 9mm) being 166. Eventually the Mauser factory redesigned the model to fire the larger and more powerful .45 ACP cartridge that was being tested by the U.S. Military, and it is estimated that not more than an handful of this model (in .45 ACP) were ever produced due to the start of WWI, when all production of this model was stopped. The left side of the slide is marked "WAFFENFABRIK MAUSER A.-G.OBERNDORF A.N. MAUSER'S PATENT". The serial number "1" is stamped on rear of the frame, the side of the barrel lug, the underside of the side plate on the frame and safety lever, the rear of the magazine and the trigger plate with no other visible numbers present. It is fitted with a one-piece checkered wraparound walnut grip. It is complete with one original polished steel magazine with a rust blued base. This exceptional pistol has the high polish rust blue metal finish with the trigger, operating rod guide, and extractor heat blued with some of the internal parts having a straw colored finish. Provenance: The Robert Bretherton Collection; Property of a Gentleman

Very fine with 97% of an old professional restored blue finish, currently only showing wear on the edges and high points. The grips are also very fine with minor handling marks on both sides. Mechanically needs work as the mechanism is stiff and does not engage the striker which is absent. This is an extremely rare and significant, serial number 1 Mauser prototype semi-automatic pistol in .45 ACP.