In Russian OOB have ended slots the weapon.

[Marcello]

1975 does not make much sense to me as a subdivision.
At the most you could make 1946-1991 and then another OOB covering the modern Russia, which you can then fill with all the sort of fancy toys.

Personally I have had a similar problem with my mod, as the iraqis started after WW2 with a british equipped army with a few US weapons thrown in, then switched to soviet arms and finally went to international shopping spree in the 80's. Neverthless I believe I am managing to make it work. For example the fact that each gun can fire two AP rounds has saved me a few weapons slots . Perhaps an in depth analysis of the russian OOB could generate a few savings.