ZB-47

The ZB-47 is a prototype submachine gun developed by Zbrojovka Brno. It was advertised as a high-capacity submachine gun for general usage by forces behind lines^[1] & for its low profile. The mechanism is open bolt, simple blowback and uses the force from the recoil to turn a wheel, feeding the next round.^[2]

Logistical issues

The design of the ZB47's straight magazine required specially-made straight-walled cartridges.^[2] Typical cartridges have a slight conical shape which reduces friction when extracting, as the brass expands slightly to the chamber walls. Zbrojovka Brno decided that designing custom straight-walled 9mm Parabellum was a better choice, as it meant the production of magazines could be simplified; losing the need to bend curves.