If the machinery came from Britain why would the ammo be loaded with a 174 grain flat base solid lead core bullet, rather than the MkVII bullet or the Boatail MkVIII bullets. Also if the machinery were from britain why is the ammo Boxer Primed when British .303 is all berdan Primed?
Why is the powder charge Olin Ball rather than either Cordite or IMR3031?
And lastly why is the brass of a different color than British brass and the rims not quite as thick.
During that time frame Britian could not even produce enough ammo to supply its own forces, how could they build ammunition plants for Greece?
As for thin rims on recent manufacture .303 cases, and the similar thin rim of the Kragcases.
Max rim thickness of the Krag is .064 just as the british .303 specs would call for, but US Army specs for the Krag rim is .060.
Old commercial krag brass often mikes at .064 or higher, the reason it was once recommended for .303 handloads. More recent production mikes at .059 or there abouts, closer to the army specs.
I suspect that commercial Krag cases at one time were made on the same machinery used for .303 brass. In more recent times the reverse has come about, .303 cases now being made on the machinery set up to make Krag cases to the original specs. There may be other rimmed cartridges in this class that also call for the thinner rim.