Were they designated 'GK' in European catalog listings and / or Steyr literature prior to 1956?
I do not have a catalog from between 1952 and 1956, but I have some rifles, I can check the reality, delivered to the customer.
There is an Model 1950, that has features from the Model 1952, and I have a Model 1952, that has features from the GK.
It seems to be, that improvements were put into production as soon and as fast as possible.
In the 50's, the US was the most important market for Steyr and they produced, whatever Stoeger ordered.
.458, .338, .358 .308 .264 are examples.
The saying goes...., the M1950 had a very slim and filigree stock, made for a light rifle to hunt the Austrian montains.
This stock often was brocken, especially in the rough hands of American soldiers in Europe.
Instead of "Mannlicher-Schoenauer", it quickly it earned its nickname "Mannlicher-Schaftbruch" (Mannlicher-Stock break).
Stoeger spoke a word of power, and the stock of the M1952 was made much more durable.
Sorry for capturing the thread again.
My "Do it all 9,3x62 MS", stock finished and new blueing, waiting vor a new scope.
HWL