The 45mm at gun was widely used until the end of the war. In fact, one could say it was the Russian version of a Bazooka, because it equipped infantry bataillons with their own anti tank firepower. The 76mm Zis 3 has already been shown. AFAIK there was no 85mm at gun (only an AA gun) and there are no plans for the really late war 100mm gun, which was pretty rare.