AUSTRIAN StG58 MAGAZINE CHARGING ADAPTOR
Information and pics courtesy of Mr Pogo

It's believed this MCA was one supplied with the Austrian StG58 rifle.  All these rifles appear to have a matching serial numbered charger issued with them, this will pertain to the original rifles purchased from FN in 1958.

Markings: The serial number is 2.0 mm high, the "5" stamped on the back joining flange is 4.0 mm high.

Finish: Black paint over phosphated finish.