Rafael Mendoza was Mexico’s premier domestic arms designer, and the Model 1934 LMG is probably his most successful design. He began work on it in 1929, and it entered testing with the Mexican Army in 1932. It was formally accepted by the Mexican Army in 1934 (hence the designation) and would serve into the mid 1950s. Mendoza was a private civilian, but production of the gun took place in the state-owned National Arms Factory in Mexico City, with Mendoza himself receiving no royalty or licensing fees. Instead, his company was given a contract to make the magazines for the guns.
Mechanically speaking, the Mendoza 1934 is a gas-operated, rotating bolt, magazine-fed LMG chambered for 7mm Mauser (the standard Mexican military cartridge at that time). Production actually began in 1939, and would continue into the 1950s with about 5,000 made in total. The main purchaser was the Mexican military, but some were also exported to Guatemala, Costa Rica, and Cuba (both Batista and Castro). With he end of World War Two, there was a huge glut of American surplus arms, and Mexico adopted the BAR and the Browning 1919, which replaced the Mendoza in Mexican front line service.
If you are interested in more details about the Mendoza 1934 or any of Rafael Mendoza’s other designs, I highly recommend Luis Eduardo Gonzales’ book on Mendoza, available in English in both print and Kindle versions:
Many thanks to the Royal Museum of the Armed Forces and Military History in Brussels for access to this very rare piece! Check them out here: