It would seem plausible to suppose that perhaps 'GK' did originally indicate the change, with Model 1952, to the swept back bolt handle. With the new MC stock for Model 1956 and the later MCA having been produced primarily for sales to the U.S., production continued on the prior model (GK, or Model 1952) for European buyers and, as advised in the '60 Stoeger, for U.S. buyers who preferred a "conventional style stock as used in Europe".

As the low cheekpiece stock had last been standard on the Model 1952, or GK, that was how it was to be ordered. Perhaps due to convention it would become assumed that 'GK' stood for 'Gerader Kolben' much the same as many believe that 'Jeep' came from an abbreviation of the words, 'general purpose' (it did not).