Task: Question Understanding
Input (English): Context : the German Army (1940) forbade the firing of more than 250 rounds in a single burst and indicated a sustained rate of no more than 300--350 rounds per minute to minimize barrel wear and overheating, although the excellent quick-change barrel design helped a great deal. Burst limits are typical on non-water-cooled automatic weapons, and slower-firing Allied guns such as the M1919 also had limits; they fired at a slower rate, but lacked a quick-change barrel, and so the operator had to limit his fire to a few hundred rounds per minute to allow the barrel to cool between bursts. Due to the slower firing rate, this led to a longer period of time spent shooting, but a roughly equivalent total number of rounds fired. Operationally, the MG 42's main drawback was that it could consume ammunition at such a high rate that it was very difficult to keep firing during offensive actions, because ammunition had to be carried forward on a continuous basis. This was also a problem at the end of the war with inexperienced German troops, good fire discipline was a must and the level of training that the German infantry was receiving was poor. The method of barrel change made the MG 42 unsuitable for secondary or co-axial armament on World War II era German tanks with the exception 
Question : In what year did MG 42 enter service?
Output (English): service entry