Technically, Maschinengewehr 34 (MG-34) was not a Nazi Wunderwaffe, because it was first tested in 1929 – well before Nazis came to power. However, it was officially introduced in 1934, and issued to Reichswehr units in 1936 (after the Nazis came to power), so I found it appropriate to include this remarkable weapon in this list.
MG 34 was a genuinely revolutionary weapon, because it introduced a radically new concept in automatic firepower – the Universal Machine Gun (currently pretty much standard worldwide).
And thus is generally considered the world’s first general-purpose machine gun (GPMG) which can be mounted on bipods, tripods, and vehicles as infantry support weapons. In other words, to serve as both light- and medium machine gun.
MG 34 was arguably the most advanced machine gun in the world at the time of its deployment. Its combination of exceptional mobility – being light enough to be carried by one man – and high rate of fire (of up to 900 rounds per minute) was unmatched (and fearsome).
The MG 34 was the mainstay of German Army support weapons from the time of its first issue in 1936 until 1942, when it was supplanted by the next generation Maschinengewehr 42 (MG 42) – essentially a cheaper and simplified version of MG 34.
MG 42 was far better suited for mass production and was more reliable and easier to operate than its predecessor. It is most notable for its very high cyclic rate for a gun using full power service cartridges, averaging about 1,200 rounds per minute compared to around 850 for the MG 34, and perhaps 450 to 600 for other common machine guns like the American M1919 Browning or British Bren.
This rate of fire made it extremely effective in providing suppressive fire, and its unique sound led to it being nicknamed “Hitler’s buzzsaw“.
The German tactical infantry doctrine based a squad’s firepower on the general-purpose machine gun in the light machine gun role so that the role of the rifleman (armed with bolt-action Mauser carbine) was largely to carry ammunition and provide covering fire for the machine gunners.
The advantage of the general purpose machine gun concept was that it added greatly to the overall volume of fire that could be put out by a squad-sized unit. With predictable (and devastating) consequences for their opponents on a battlefield.
The MG 42’s lineage continued well past Nazi Germany’s defeat, forming the basis for the nearly identical MG1 (MG 42/59), chambered in 7.62×51mm NATO cartridge Which subsequently evolved into the MG1A3, and later the MG 3 (standard GPMG of German Bundeswehr).
It also spawned the Yugoslav nearly identical Zastava M53, Swiss MG 51 and SIG MG 710-3, Austrian MG 74, and the Spanish 5.56×45mm NATO Ameli light machine gun, and lent many design elements to the American M60 and Belgian MAG – two standard NATO GPMG.