The Germans fielded the unrelated early 2 cm Flak 28 just after World War I, but the Treaty of Versailles outlawed these weapons and they were sold to Switzerland.

It proved to have feeding problems and would often jam, which was offset to some degree by its undersized 20 round-magazine which tended to make reloading a frequent necessity.

The MG C/30L variant was also used experimentally as an aircraft weapon, notably on the Heinkel He 112, where its high power allowed it to penetrate armoured cars and the light tanks of the era during the Spanish Civil War.

Rheinmetall[N 1] responded with the 2 cm FlaK 38, which was otherwise similar but increased the rate of fire by 220 RPM and slightly lowered overall weight to 420 kg.

It featured a dramatically simplified mount using a tripod that raised the entire gun off the ground, with the additional benefit of allowing the weapon to be set up on an uneven surface.

Even as the FlaK 30 was entering service, the Luftwaffe and Heer (army) branches of the Wehrmacht had doubts about its effectiveness, given the ever-increasing speeds of low-altitude fighter-bombers and attack aircraft.

The Flakvierling weapon consisted of quad-mounted 2 cm FlaK 38 AA guns with collapsing seats, folding handles, and ammunition racks.

Automatic weapons are typically limited to roughly 100 rounds per minute per barrel to give time for the heat to dissipate, although this can be exceeded for short periods if the firing window is brief.

Several field modifications existed in the war, including mounting the Flakvierling onto 3 Panzer IVs, made by SS-Hauptsturmführer Karl Wilhelm Krause with the 12th SS Panzer Division Hitlerjugend (which inspired the Wirbelwind), as well as mounting it on a captured T-34 and a Bergepanther (made by Schwere Panzerjäger-Abteilung 653).

In Kriegsmarine use, it was fitted to E-boats, U-boats, Siebel ferries and ships to provide short-range anti-aircraft defence, and was also employed in fixed installations around ports, harbours and other strategic naval targets.

A range of 20x138B ammunition was manufactured for 2 cm Flak weapons, the more commonly used types are listed on the following table.

in German notation) and a number of different AP types including a high-velocity PzGr 40 round with a tungsten carbide core in an aluminium body.