Soviet serial numbers after 1936. . .
. . . were in a format of two Cyrillic letters followed by four numbers, as in AA0001 to AA9999 then two different letters were used with the numerals beginning with 0001 again.
This is the same for all Soviet small arms of the period, whether its was handguns (Nagant revolvers, TT-33 pistols), rifles (91/30. 38. 44, SVT-38, SVT-40, whatever). Two letters then four numbers, then start over with different letters.
Unfortunately we do not know what the letter-sequence was - it is very apparent and obvious that they were not used in any sort of order.
I doubt that these wartime records exist (if they do, no researcher has yet to find them anywhere).