“Most of the ammunition for our Sten gun is Italian, or rather made in Germany for Italy. I fancy this must be the first weapon the British army has had whose bore was measured in the millimetres instead of inches. They were going to make a new cheap automatic weapon, and having the vast stocks of ammunition captured in Abyssinia handy, manufactured the guns to fit the cartridges instead of the other way about. The advantage is that the ammunition of almost any continental submachine gun will fit it. It will be interesting to see whether the Germans or Japanese come out with a .303 weapon to git captured British ammunition.”

Orwell diary, 22.09.1942 (link)