Hotchkiss M1929 machine gun
The 13.2 mm Hotchkiss machine gun model 1929, often simplified to Hotchkiss M1929 machine gun, and the like, was a heavy machine gun designed and manufactured by Hotchkiss et Cie from the late 1920s until World War II which saw service with various nations' forces, including Italy and Japan where the gun was built under license. Development. In the late 1920s, Hotchkiss proposed a range of anti-aircraft automatic weapons in the 13.2, 25 and 37 mm calibers. They were all based on the same type of gas-operated action, similar to the one used in  the 8 mm Hotchkiss Mle 1914 machine gun, which had proven extremely reliable during World War I and was still in service. This led to the production of the 13.2 mm Hotchkiss machine gun model 1929, often called the Hotchkiss M1929. Performance. The Hotchkiss M1929 machine gun had a cyclic rate of fire of 450 rounds per minute, but their practical sustained rate of fire was just 200-250 rounds per minute due to limited magazine capacity. Majority of Hotchkiss M1929 machine guns was fed by overhead 30 round curved box magazines. These magazines would run empty in just 4  seconds, requiring frequent magazine changes which limited their rate of fire. Cartridges. The Hotchkiss M1929 machine gun was initially chambered for the cartridge "13.2 × 99 mm Hotchkiss "Long"", which more or less was a 12.7 × 99 mm Browning (.50 BMG) cartridge necked up to 13.2 mm caliber. This cartridge however proved to wear out gun barrels too quickly and to alleviate this inconvenience Hotchkiss introduced a new cartridge for the M1929 machine gun in 1935, featuring a slightly shorter cartridge case and reworked projectile shape, becoming the cartridge "13.2 x 96 mm Hotchkiss "Short"". The new cartridge was  practically identical to the original 13.2 x 99 mm cartridge except for the length of the neck, reducing the full case length to 96 mm. This minimal change was done so that existing weapons and the production line did not require any modification to fire the new cartridge, but was sufficient enough to fix the barrel wear issue. Configurations. The Hotchkiss M1929 machine gun came in a number of different configurations depending on their intended role. There were single, double and quadruple barreled anti-aircraft weapons on a high-angle pedestal and tripod mounts, as well as low-angle bipod  mounts for anti-tank and heavy machine gun roles. French infantry commanders, who had expressed interest in acquiring light anti-aircraft guns, refused to accept the 13.2 mm. They argued that the heavy bullets falling down could be dangerous to friendly troops, and preferred larger calibers for which self-destructing shells were available. But the 13.2 mm Hotchkiss saw extensive use as a naval gun and was also chosen by the French cavalry for some of its armored vehicles. Service. As a ground-based anti-aircraft weapon. The French Air Force used the M1929, designated as mitrailleuse de 13.2 mm  CA mle 1930, for close-range defense of its airfields and other strategic places. It came in two versions: As a naval weapon. Early in World War II, the French, Italian and Japanese navies were using twin (CAD Mle 1929 - "Contre Avions Double") and quadruple (CAQ mle 1929 - "Contre Avions Quadruple") mountings on many of their warships. French warships that were refitted in the United States in 1943, such as the battleship "Richelieu" or the destroyer , had their 13.2 mm machine guns replaced by more powerful Oerlikon 20 mm cannons. In Italy, the Società Italiana Ernesto Breda produced the gun  under license as the Breda Mod.31 from 1931 onwards. It was used as an anti-aircraft gun aboard ships, submarines, and armored trains of the Royal Italian Navy. After World War II it was used on the patrol boats of the Guardia di Finanza. The Spanish Navy bought the weapon in December 1935 and used it during the Civil War (where it was mounted on several Republican Navy destroyers and cruisers). The "Pirotecnia Militar" Army Ammunition plant (Sevilla) produced its cartridges after 1939. As a ground weapon. Several self-propelled anti-aircraft combinations were tested in the 1930s, with Citroën -Kegresse or Berliet chassis, but none was mass-produced. The 13.2 mm Hotchkiss was used on the Belgian T15 and the French AMR 35 light tanks as well as on the White-Laffly AMD 80 armoured car and on fortifications. The Free French used field-modified self-propelled mountings, with guns recovered from French ships, in North-East Africa in 1942. The Breda Mod.31 was used as an anti-aircraft and heavy machine gun on command tanks of the Royal Italian Army as well as on L3/33 light tanks sold to Brazil. The Japanese mounted license-produced version of the  gun on a number of Type 92 Heavy armored Cars which had initially been armed with only a pair of 6.5mm machine guns.