PROTOTYPES to PRODUCTION
There was a huge difference between making a few prototypes and putting the gun into production. The pistol needed to be accurate, reliable and durable, but also cost effective. Given the limitations of 19th century manufacturing, every step was a major challenge!
Manufacturing and Assembly
Parts were made one at a time, laboriously machined by individual operators from milling machines and lathes, usually powered from leather belts attached to an overhead drive shaft. Imagine having a pile of parts that almost fit together but have to be individually hand fitted in order to make a precision automatic pistol work.
Assemblers filed and ground as necessary to insure proper fit and function. In the process, the parts were numbered, in part so assemblers could keep track of which parts went to which pistols. Most German and Austrian guns had their parts matched with the last few digits of the serial number; Spanish guns were customarily assigned an independent assembly number.
Another challenge was that the metal parts required different finishes and hardening processes to make them work in their designated functions. This was not a one type of metal fits all process. As such different finishes including rust bluing, fire blue, case hardening, and straw coloring were applied. Also the metal had to be of different hardness depending on its function.
The Mauser C96, Luger and FN 1899 designs were all commercially successful. These pistols and their latter variants were produced in great numbers. But the Legacy of the automatic pistols of the 19th Century is not a few successful designs it is every pistol of an automatic design that came thereafter. All the foundational design elements were worked out in the 1890s. What came later through today in semi-automatic pistols are just refinements.