s.S. Patrone. The s.S. Patrone had an extreme range of approximately . From its 1914 introduction the s.S. Patrone was mainly issued for aerial combat and as of 1918 in the later stages of World War I to infantry machine gunners. Another early-WWI improvement introduced in 1915 was a muzzle booster, a patent-protected Vickers invention, which was designated Rückstossverstärker 08 S. Thanks to that MG 08 came up to its British and Russian analogs with their Vickers-licensed recoil boosters in its rate of fire (up from about 300-350 to 450-600 rds/min) and reliability. Training and use Training was regulated by the Field Service Regulations of 1908, providing the German Army six years to train with the guns before the outbreak of World War I. MG 08/15 The MG 08/15 was the "rather misguided attempt" at a lightened and thus more portable light machine gun from the standard MG 08, produced by "stepping-down" the upper rear and lower forward corners of the original MG 08's rectangular-outline receiver and breech assembly, and reducing the cooling jacket's diameter to . It was tested as a prototype in 1915 by a team of weapon designers under the direction of an Oberst, Friedrich von Merkatz; this became the MG 08/15. The MG 08/15 had been designed around the concept of portability, such as the French Chauchat, which meant that the firepower of a machine gun could be taken forward conveniently by assaulting troops, and moved between positions for tactical fire support; as such, the MG 08/15 was to be manned by two trained infantrymen, a shooter and an ammo bearer. In the attack the weapon would be fired on the move (marching fire) while on the defense the team would make use of the bipod from the prone position. To accomplish that, the MG 08/15 had a short bipod rather than a heavy four-legged sled mount, plus a wooden gunstock and a pistol grip. At the MG 08/15 had minimal weight savings over the MG 08, being "a cumbersome beast to use in the assault." Intended to provide increased mobility of infantry automatic fire, it nevertheless remained a bulky water-cooled weapon that was quite demanding on the crews and never on par with its rivals, the Chauchat and the Lewis Gun. Accurate fire was difficult to achieve and usually in short bursts only. The fabric ammunition belts were prone to stretching and there were cartridge