I heard that the greeks were not given M2 factory spec information from the US . They had to reverse engineer the '06 to fit the M1 Garands they had . The M1s were made with a little bit longer chamber neck area for better functioning under dirt and grime than the manually operated '03 . Thier ammo spec works fine in an M1 , but may be a hair too long in an "03 . It's this extra hair that may cause some stickiness. No real danger and why this disappears on trimed reloads using the same brass.
Chris