I kind of suspect that Greece at the time was getting on the .30 calibre band wagon with a large stock of 6.5mm rifles on hand and was considering a cheap option of using the old rifles as a platform to do so. Sort of like Italy's limited attempt to rebore the 6.5mm Carcano to 7.35mm.

I suppose Greece gave that idea up either due to the wars and civil unrest effecting manufacturing and distribution, or by the US and NATO supplying them with a bunch of state of the art weapons after WWII to fight the communist factions during the start of the Cold War.

It will be interesting to find out more though.