I think the biggest ways the MG34 and the MG42 were different from their predecessors in German service at least was that they were lighter and that they had quick change barrels. The older water cooled machine guns, which did have some advantages, were simply too heavy and difficult to move around. They needed a whole squad to employ. Everyone has fairly similiar general purpose machine guns now but apparently a quick change barrel is not so important as it was considered then. Of course with the high rate of fire of an MG42, maybe it needed it more than other guns.
Obviously the MG42 was a redesign of the MG34 and the MG42 was obviously the inspiration for the M60, though everything I've read said that some design features actually came from other weapons. It's interesting to consider that the replacement for the M60 is actually an older design that was introduced either at the same time or a little earlier.
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
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