9×25mm Mauser

The 9×25mm Mauser (or 9mm Mauser Export) was a cartridge developed for the Mauser C96 service pistol. The cartridge was first produced by DWM in 1907 and later by German munitions makers Geco (Gustav Genschow & Co.) and RWS (Rheinische-Westfalische Sprengstoff AG) through World War II. Other manufacturers included Société Française des Munitions of Paris, France as well as various munitions factories in Austria and Hungary in the 1930s and 1940s.

Mauser pistols in this relatively powerful caliber were primarily intended for export to Africa, Asia and South America. The 9mm Mauser Export cartridge was produced from 1907 to 1914 and then later from approximately 1930 to 1945.

The basis of this cartridge was the 7.63×25mm Mauser. The case length is the same as the 7.63×25mm Mauser, but the case is straight and does not have a bottleneck shape. This cartridge headspaces on the mouth of the case. The 9 mm Mauser should not be confused with the 9mm Parabellum (9x19mm Luger) or the 9x23mm Steyr.

As the German Army seemed to show more official interest in the P-08 Luger than the C-96, Mauser developed a new design. In 1906, Mauser introduced the Model 1906-08 (or C/06-08) pistol in 9×25mm Mauser caliber, which used a detachable box magazine of 6, 10 or 15 rounds. This pistol had a similar layout to the C-96, with the magazine situated in front of the trigger group, but incorporated a locking system that was considerably different. Interested purchasers included the German and Brazilian armies. The pistol was never manufactured for commercial sale.

In the 1930s a handful of Austrian, Hungarian and Swiss submachine guns and machine carbines were chambered for this caliber. Originally known as the Steyr-Solothurn S1-100, the Steyr MP30 and MP34 were adopted by the Austrian Army and police and manufactured until 1940. SIG automatic carbine models MKMO, MKMS, MKPO and MKPS in this caliber were produced in Switzerland until the end of 1942. The Pál Király-designed Géppisztoly 39M and 43M in 9×25mm Mauser were produced by Danuvia in Hungary from 1939 through the end of World War II.

Reloading
Reloadable cartridge cases may be produced by resizing and trimming 9mm Winchester Magnum brass. A reasonable starting point for load development would be .38 ACP (not .38 Super) load data. The .38 Super data may possibly be more consistent with the original factory loading, as these had a claimed muzzle velocity of approx. 1362 fps with a 128 gr. bullet. The 8th edition of Cartridges of the World has a listing in the entry for 9mm Mauser using a 125 gr. bullet with a heavier charge of Blue Dot powder than is normally listed as the maximum for 124 gr. jacketed bullets in the .38 Super. Old loading data may incorporate more powerful loads than is intended with modern components, but care should be taken not to underload the cartridge to ensure proper cycling in an auto-loading firearm.