The Borchardt C-93 (Construktion 93) is a semi-automatic pistol designed by German firearms inventor and engineer Hugo Borchardt (1844–1921). Borchardt's assistant at the time, Georg Luger, also claimed to have worked on several elements of the design. Borchardt also developed the proprietary high-velocity bottlenecked 7.65×25mm cartridge for use with the pistol. The C-93 holds the distinction of being the first commercially successful mass-produced semi-automatic pistol.[1]

The C-93 pistol used a toggle-lock recoil action system based upon the Maxim machine gun's toggle-bolt design. When the gun is fired, a two-piece arm rises up and flexes as the gun recoils backwards, thus allowing the breech to unlock and release the empty cartridge case. The cartridge used in the Borchardt C-93 was the basis for the primary cartridge used in the later Mauser C96 pistol, the 7.63×25mm Mauser. They have the same dimensions, but the 7.63mm Mauser generally had a more powerful powder charge (contemporary loading data indicated it took approximately 20% more powder than the Borchardt), and is considered to be too strong to be used in a Borchardt C-93. Nonetheless, cartridge boxes from some manufacturers were marked "For Borchardt and Mauser Automatic Pistols".

Following the completion of the final design, Borchardt's employer at the time, the German arms company Deutsche Waffen- und Munitionsfabriken (DWM) tasked one of Borchardt's co-workers, a Mister Georg Luger, to promote the Borchardt pistol in both military and commercial channels. The pistol was tested by the U.S. Navy as early as 1894 and later by the U.S. Army. Although it was accurate and its rate of fire was rapid, the Borchardt pistol was expensive to produce and unwieldy to handle due to its almost vertical grip and awkward distribution of weight. Furthermore, its recoil was unexpectedly powerful, owing to the strength of its 7.65mm cartridge. These design shortcomings were noted during the Swiss Army's field tests, and the comments of the Swiss officers were relayed back to Borchardt. However, Borchardt refused to make any changes to his original design, as he believed it to already be perfectly adequate. DWM then appointed Georg Luger to make a number of improvements to the pistol. Luger took the Borchardt design and modified it to use the shorter 7.65×21mm Parabellum cartridge, which allowed him to incorporate a shorter stroke of the toggle mechanism and a narrower, more angular grip. Luger's revised design eventually became the Luger P08 pistol.[2]