I had some Greek .303.
Out of all the rounds I fired, one would not chamber.
It has a poorly formed case head.
Right above the rim is a rough band of brass.
It looks a little like the belt you see on belted magnums, but it's right above the rim, there's no extra space for the extractor hook.
It would never chamber, and I still have it.
Even so, if I could find any more Greek .303 I would snatch it up quick.
It never had a dead primer and the accuracy was was probably better than my eyesight.