Hi Zhang,
In an earlier post on this topic Jacques mentions that some cameras with a serial number as high as 150,000 still have this hole in the pressure plate.
So I guess this was until 1941, just before the factory was evacuated, and seven years after production began.
My own personal thoughts are that the punch used by Fed to stamp out these parts was not modified when the outer hole in the body was discontinued, and that that the factory continued to use the punch as it was. It doesn't make sense to me that Fed would have produced 150,000 of these pressure plates so early in production.
Perhaps having to leave Kharkov then forced Fed to produce a new punch for the next production.
I will be home in the UK in two weeks time and will check my own cameras to see which is the highest serial number still with the hole in the pressure plate.
Best regards, Jim.


