And what good would antique equipment be, if it even exists and is in working order, not to mention arsenals from three different nations with completely different standards of ammo, spares, etc.?
Also Stalin's slaughter of so many Red Army officers had nothing to do with actions or opinions on the victims' part and everything to do with his own murderous paranoia. The truth of the matter is that after 17 years of Stalin's leadership in arming and industrializing any rational German leader, as opposed to the bigot Hitler, would have destroyed the USSR.