This thread to try and clarify what can be exactly this Fed, to answer Alfa2 questions...
First, the subject is a contradiction in itself. The 1b series (with the engravind in italic letters) begins around the s/n 6000. So, this Fed 1b, with such an early number, should not exist.
To explain that, it seems there are two possibilities:
- an error of engraving with a missing cipher,
- the engraving of a former s/n on a "newer" cover by the factory, because of an important repair. Leitz had done the same with their Leicas.
http://www.ussrphoto.com/UserContent/422016_IMG_2266.JPG
The comparison between these three Fed 1b cameras shows that this s/n 4580 belongs to the same variety as the s/n 25617:
- it has a broad engraving,
- the shape of the cover, on the left, is more curved and angular than on the 21225.
With the cameras I have, I cannot be more precise about the limits. But you can have a look at Alexey's site he has too several intereting 1b-s : http://ussrcameras.ru/?rp=1&action=tovar&tovar_category=385