Did you know that before AK-47, there was a “Lightning” submachine gun? It was one of many “homemade” weapons used in the Warsaw Uprising

 The “Błyskawica” (Lightning), was a submachine gun produced by the Home Army (underground partisan army) in occupied Poland. Together with a Polish version of the Sten submachine gun, from which it took some design elements, it was the only weapon mass-produced covertly in occupied Europe during World War II.

The design was based on two of the most popular submachine guns of the era. The external construction with a retractable butt and magazine mounted under the gun was borrowed from the successful German MP 40. The internal design of the mechanism was modeled after the British Sten, Blowback, with an open bolt. It offered good performance and high reliability. The weapon was designed so that resistance army members could use any captured stocks of German MP40 ammunition cartridges. That’s right, ammo they took from the Germans, not necessarily in a friendly fashion.