Staff Writer (Updated: 2/15/2016):
The driving principle behind the revolutionary Mondragon Rifle was its use of a gas-cylinder operation (tapped from the barrel) which drove a piston and featured a rotating bolt with locking lugs and a grooved receiver. Such a design was ahead of its time in a world where trust was still placed in the proven yet cumbersome manual bolt-action. Another unique facet of the rifle - and this instilled into its design by governing authorities who mistrusted such automated mechanical functions in weaponry - was that the automatic system could be disconnected from the bolt and allow the rifle to be fired as a standard, "straight-pull" bolt-action weapon. The Mondragon Rifle was chambered to fire the 7x57mm Spanish Mauser cartridge to which the base rifle was produced with an eight round box magazine.
Production of the Mondragon Rifle began in 1887 to which some 1,175,400 examples would be ultimately produced. However, early versions were produced overseas as local Mexican factories lacked the ability to manufacturer such a complex weapon and little interest was shown in the neighboring United States. As such, the Swiss firm of Schweizerische Industrie Gesellschaft firm of Switzerland (better known today by its initials of "SIG"), received an initial contract for or some 4,000 production rifles. Deliveries began soon after with the first rifles arriving in Mexico in 1901 under the Mexican Army designation of "Fusil Mondragon Modelo 1900".
Once in practice, the Mondragon Rifle showcased the quality standards common to Swiss-made arms and Mondragon's engineering prowess shown through. The weapon proved a very capable and powerful man-stopper and the automated repeating action was a very advanced concept for a rifle in this period. However, the system as a whole proved rather unwieldy during full-automatic fire no thanks to the inherently violent recoil (common to many early repeating rifles) and, as such, accuracy in this mode was rather poor at distance.
The Mondragon Rifle line was broadened with the development of a light machine gun model. This version introduced a bipod for forward support as well as higher magazine counts (30- and 100-round drums became available). As a light machine gun, the type could be used to suppress enemy movements or assist as a portable infantry squad support light machine gun similar to today's FN Minimi model. The Mondragon Light Machine Gun (LMG) served in this role with the Mexican Army until it was replaced by the Mendoza M1943 General Purpose Machine Gun (GPMG) of 1943.