The Parabellum MG14 was a 7.92 mm caliber World War I machine gun built by Deutsche Waffen und Munitionsfabriken. It was an adaptation of their Maschinengewehr 08 gun intended for use on aircraft and zeppelins. The MG08's belt-style ammunition feed was enclosed in a drum, the recoil casing was lightened, and the cooling jacket was modified for air- instead of water-cooling. The rate of fire was 700 rounds/minute. Leutnant Kurt Wintgens' Fokker Eindecker prototype. "E.5/15", which used a Parabellum MG14 as its synchronized armament in July 1915.
The MG14 first appeared in 1914, but was rendered largely obsolete the following year with the introduction of the gun synchroniser which allowed pilots to fire between their aircraft's propeller blades. The MG14 was tried with the pioneering Fokker Stangensteuerung synchronizer on the Fokker E.I pre-production prototypes, but the gun's reliability in this installation eventually proved to be unsatisfactory, even though its closed bolt firing cycle was a desirable feature for synchronisation. It continued in service in applications where a synchroniser was unnecessary, such as armament for observers in reconnaissance aircraft, or defensive gunners aboard Zeppelins.
The Schwarzlose, was of simple design and featured an unusual, delayed blowback mechanism which contained only a single spring. The initial variants of the M.07/12 had a cyclic rate of about 400 rounds/m, but this was later increased to 580 rounds/m during World War I by fitting the mechanism with a stronger spring. The Schwarzlose was a robust and reliable weapon in its intended role as an infantry weapon, but unlike the highly adaptable Maxim-derived machine guns, met with less success when it was used in roles it had not been designed for.
The Schwarzlose saw service with the Austro-Hungarian Luftfahrtruppe during World War I as an aircraft machine gun, a role for which it was not entirely suited. The Schwarzlose was used both as a fixed forward firing gun and as a flexible, ring mounted, defensive weapon.
Synchronizing the Schwarzlose for use in fighters turned out to be a difficult engineering challenge. A critical factor in sychronization is the time delay between the trigger movement and the moment when the bullet leaves the barrel, as during this delay the propeller will continue to rotate, moving over an angle that also varies with engine rpm. Because of the relatively long delay time of the Schwarzlose M7/12, the synchronization systems that were developed could be operated safely only in a narrow band of engine rpm. Therefore the Austro-Hungarian fighters were equipped with large and prominent tachometers in the cockpit. The M16 version of the gun could be synchronized with greater accuracy, but a widened engine rpm restriction still had to be respected, except for aircraft equipped with Daimler synchronization gear. The result was never entirely satisfactory and Austro-Hungarian aircraft thus armed usually carried the Kravics indicator, an ingenious bullet strike sensor on the propeller, to warn the pilot of a malfunction in the synchronization mechanism.
Until these synchronization problems had been overcome, it was not uncommon to see the Schwarzlose deployed in a removable forward firing Type-II VK gun container which had been developed by the Luftfahrtruppe's Versuchs Kompanie at Fischamend. The Type-II VK, which received the macabre nickname "baby coffin" due to its shape, is remarkable in that it was possibly the first example of what today would be called a "gun pod". It was usually mounted on the centerline of the upper wing of Austro-Hungarian fighters and two-seat combat aircraft during the early phases of World War I and remained in use on two-seat combat aircraft until the end of the war. In its role as an aircraft weapon the Schwarzlose was initially used unmodified other than that the distinctive cone shaped flash-hider seen on most of the infantry weapons was removed. The Schwarzlose was further modified for aircraft use by cutting slots into the water jacket to facilitate air cooling. In 1916 the water jacket was removed entirely and the resulting weapon was re-designated as the Schwarzlose MG-16 and MG-16A when fitted with a stronger spring and a blowback enhancer to increase the guns cyclic rate which was eventually brought up to 880 rounds per minute in some versions of the MG-16A. As a defensive ring mounted gun the Schwarzlose usually retained its normal twin firing handles and trigger button although some MG-16 aircraft guns were fitted with enlarged pistol shaped handles and a handgun style trigger. All ring mounted defensive guns were equipped with specialized sights and a box for the ammunition belt which allowed quick and trouble-free reloading. After the end of World War I the Schwarzlose saw limited use as an aircraft gun with various East European air forces. The best known post war operator of the Schwarzlose was probably the Polish air force who acquired and used significant numbers of surplus Austro-Hungarian aircraft and used them against Soviet forces during the Polish-Bolshevik War. The Schwarzlose was, however, quickly phased out of service as an aircraft weapon when more suitable equipment became available.
The LMG 08 is an almost direct copy of Hiram S. Maxim's original 1884 Maxim Gun. It was deployed by the German air service as a replacement for the aging Parabellum Gun. The Parabellum had not proved suitable for use with new Interrupter Gear. Implementing the LMG 08 was not without its own set of problems. It quickly became apparent that a water cooled weapon was not suited for aircraft. An air-cooled jacket was the answer to this problem. Modifications were needed to cool the barrel. The standard water jackets were manufactured with perforations to provide air flow to cooling the barrel of the gun. This modification retained enough structural strength to withstand the recoil of the gun. The front cover was also perforated and the trunnion was adapted on the bottom for a bolt mount.
When the MG 08/15 was introduced into service in 1915 it was soon adapted for aircraft use in a similar fashion to the 08. After modification the LMG 08/15 weighed 26 lbs compared to the original MG 08 weight of 57 lbs. One very visible modification was the change to the cocking handle (Durchladehebel). Because the guns were fixed and mounted ahead of the pilot, the normal method of clearing blockages, loading and unloading could not be practiced. The LMG 08/15 was not without its faults. The original guns required two hands for cocking and charging. The "Kingstrom" mechanism bolted to the right side of the gun enabled one-handed operation. This too evolved into a long handle, geared to the cocking lever on later models. The knob on the cocking lever also evolved into a "half spool" shaped knob which was easier to grasp with gloved hands. There appears to be no firm rule as to when a specific style was utilised and it is thought that much of the decision was based on pilot preference.
Two other modifications were the introduced The first was rear mounted safety interlocks which made life safer for the ground crew who stood in the line of fire during engine start up. The second was round counters to track ammunition usage. There were several types of round counters used, all of them showed the number of rounds remaining. Over 23,000 LMG 08 and LMG 08/15 were manufactured at the Spandau Arsenal in Berlin, Germany. The Allies called it the "Spandau" because of the name engraved on top of the gun.
The 7.92 MM ammunition was fed into the gun on a cloth belt holding 250 or 500 rounds. An aluminum link belt was developed for both the MG/08 and MG 08/15 guns but the cloth belt was still preferred for aviation use.