Prussian-German gunsmith Andreas Wilhelm Schwarzlose developed a line of machine guns that became the standardized water-cooled medium machine gun of the Austro-Hungarian Army heading into World War 1 (1914-1918). These developments were also taken on by many European nations, from Albania and Austria to Sweden and Yugoslavia. Operational service saw the line in action from its adoption in 1905 to the end of World War 2 in 1945, such was its reach on the battlefields of the 20th Century.
The Schwarzlose machine gun adopted the appearance long-established by the Maxim design complete with its rectangular receiver, jacketed barrel section, and conical flash suppressor. It was a belt-fed weapon typically feeding from a 250-round ammunition stock and chambered for the 8x50mmR Mannlicher Austro-Hungarian rifle cartridge. Export orders also led to more localized cartridge calibers then being adopted. The action and weight of the weapon required use of a heavy-duty tripod which made the complete system weigh 42 kilograms. Overall length was 945mm with a barrel measuring 530mm. As a water-cooled weapon, the design required an accompanying water supply held in a can. This was pumped into the water jacket by way of a hose and was used to cool the barrel from overheating. With all of this in play - including ammunition handling and feeding - a typical machine gun team numbered a handful of people for proper operation in-the-field. One unique design element of the Schwarzlose approach was its use of an unlocked-breech design which, in turn, required the facilities of a short barrel than seen in its contemporaries. The short barrel helped to quickly alleviate breech pressures but led to limited effective engagement ranges and a lowered muzzle velocity for the outgoing bullet.
Original production guns were forged during in 1905 as Model 1905 and these were steadily improved through a line of similar weapons which including the upcoming Model 07 of 1907. In fact, one of the more popular breeds was the M07/12 of 1912. As proved common with other self-loading gun developments of the period, the earlier M05 and M07 production models featured an included oil pump function which was used to lubricate incoming cartridges to help ensure a smooth transaction from belt-to-breech. This feature was only supported up until 1912 to which a new, heavier bolt design was added in place of the reservoir and intended to apply additional pressure on the incoming cartridges.
In practice, the Schwarzlose was a well-liked weapon for its sheer simplicity of design and function. It was heavy as other machine guns of the period were and also as clunky due to all of the components actually making up the completed weapon system. The water-cooling feature was a key limitation of many types of the war including the famous Browning, Maxim and Vickers models. The limited range and lower muzzle velocity certainly hurt the weapon's battlefield reach but a machine gun was a machine gun in times of war - capable of mowing down inbound enemy infantry in short order as any other machine gun of the war. The inherent simplicity in design also meant that Austro-Hungarian factories could output the weapon in the necessary quantities for wartime service.
A lighter-weight version appeared for use on aircraft but this did not become an outright success - certainly not on par with competing types in the same role. The weapon was also trialed on trainable mountings in rear cockpit positions with similar limited results. Still other versions saw the weapon set atop a special turn-table mount to allow for its use as an air-defense weapon with a near-vertical elevation reach.
Active sales of Schwarzlose machine guns ended with the close of World War in 1918 and the eventual military drawdown following. Regardless, its sales and export prior to the end of the conflict ensured it a healthily long service life that saw it still in use with several armies of World War 2 (1939-1945) including both Italy and Hungary - though this was for lack of a better replacement or failure to modernize in time.