Very few were made in 1953 by Fábrica Militar “Domingo Matheu” to be used during the development of the Argentinian made StG-44 assault rifle prototypes. The term “magazine dummy” was in fact used by the designers and it’s not my own interpretation. One piece steel construction with 5.3 mm diameter hole in base.
There was also another dummy made from a standard cartridge with a hole in the case body.
Identical steel dummies also existed in 7.65 x 54 mm Mauser caliber for the Argentinian made Garand and Johnson prototypes.