Also, German weapons had a tendency to be machined to very exact specifications. Great piece of kit that will last a 100 years - problem being that
1. they won't last that long
2. overly machined = more complicated
3. high specs = lots of maintenance
Today's AKs are an example of a weapon that is simple to maintain and will continue to operate - no matter how fouled up it happens to be (more or less)
Soviet army, with their PPSH 41 created a situation where the germans faced an army with tons of firepower - while most of the germans still had their KAR98.
A few hundred PPSH41s were produced in November 1941 and another 155,000 were produced over the next five months. By spring 1942, the PPSh factories were producing roughly 3,000 units a day. The PPSh-41 was classic example of design adapted for mass production ( like the Sten). Eexcluding the barrel, its parts could be produced by a relatively unqualified workforce using simple equipment available in an auto repair garage or tin shop. Over 6 million of these weapons were produced by the end of the war.