Hello Luiz!
I won't exactly follow you.
In fact, I think that all the A were made at the same time.
Here is my (!) version.
No problem for Fed from 1955 to 1959-1960: serial numbers are ordinal numbers. They are all preceded by N° as for the Fedka series. The last # number I found: 850703 which is a 2c with rim round the rangefinder and low accessory shoe.
Then in 1960-1961 (more or less 1 year), we have some different and probably consecutive numbering systems, certainly because of the two other cameras in production: the Zarya and the Fed 3.
First (perhaps!): a ciphered system beginning by 9 (9874463 for ex: always a 1c with rim, 1/25th, one engraving and low shoe). The "N°" disappears in front of the number and we won't find it again.
Then the cipher becomes "0" (0978307 for ex. Always the same as the 9874463, but with 1/30th instead of 1/25th). If we read these numbers 9-874463 and 0-978307, we find again the ordinal number which gives the production (it's my guess!).
Then a problem. We are not far from 1 million Fed 2 really built, and the last cipher cannot allow to write 1-00000x which is the scale chosen for the 3a first version. So, taken by urgency, Fed uses an A prefix. First known: A006451 with low shoe, then stepped shoe for the other we know. Till now, all Fed 2 will have high shoes. Probably c. 100000 Fed "A" produced in 1961, I think.
After, several numbering jumps are made for the 3, so that Fed can re-utilize the 1-1xxxxx scale. We are perhaps always in 1961.
Then the 2-3xxxxx scale. I think that the 2 gives the year, so 1962 (I have no proof!) and the 3xxxxx the production. These cameras have no rim now, always the 1/30th and the stepped shoe of course. It's in that scale that I discover the first two engraved body.
After that, the 3-, 4- and 5- series: nothing to say. Years 1963 to 1965 I guess.
During all these years (since 1960), the number of production grows continuously, without interruption (as it seems!) behind the cipher. I have not found any exception. And it will continue with the following years.
No problem for 1966 which is prefixed "6". For 1967 (the anniversary!), Fed probably think that it could be fine to use a "67" prefix, so that they keep the "6" for these two years. It could explain why there is no camera with the "7" prefix. Total production: 758406 cameras (since 1960-61?), last number I found with the "6" prefix.
Then the 8 prefix, for the last Fed 2-s. We find the 2e in that scale (but in other scales too which don't belong to the regular 2). It's possible that this cipher was used for the last three years of production: 1968 to 1970 (about 100000 Fed 2 produced).
It's all I have found about the numberings of Fed2-s. No doubt the very rare passports don't help. I tried to make my suppositions as consistent as possible, but they are only suppositions! And we don't have many numbers with the 9-, 0-, and 1- systems...
Amitiés. Jacques.
