Hello,
I have recently bought a Fed 4a because of the cornered moulding of the cover. I had only seen till now rounded ones.
The evolution seems the same as on the 3a: the two first series of this camera have cornered mouldings too (see the wiki, please).
I know, it will not upset our group...
Serial number of this 4a: 4001358 (probably begins with 4000001).
Amitiés. Jacques.

http://www.ussrphoto.com/UserContent/1762009_Fed 4 001.jpg