Some facts from Wikipedia: At the opening of operation Barbarosa the Red Army had four to one advantage over the Nazis in tank numbers.
By 1941 lend lease tanks were 6.5% of Soviet tanks, about a quarter of medium and heavy tanks.
Where do you get "up to 40%" from?
Even if true my point still stands.
According t Alex Nove in 1900 there was not a metal lathe in all of Russia. They could de clinker locomotives, but not make a gear box. By 1941 they were out stripping the Germans.
That is the greatest economic achievement of the twentieth century.
(IMO the Bolsheviks were sadistic psychopaths, but credit where credit is due)
Again, you are regurgitating a myth.
I would not doubt the 4 to 1 outgunning of USSR vs. Germany. Indeed Union's army was incomparably materially superior due to decades long total dedication to military buildup, but that does not preclude the fact the industry was still barely going, and that this material advantage melted like butter within first months of war.
"probably" does not cut it.
The lie is the Soviets were bad economic managers. They pulled off the most incredible feat in industrialising their economy in less than fifty years, more liek twenty five useful years.
The millions of starved peasants, slaughtered "class enemies", exiled dissidents.... They were there too. Not pretty, not moral, not desirable, but incredible achievement nonetheless.
I am not sure, how in the context of such a system "efficiency" can be measured. But in raw capacity there has never been anything like it until the Chinese in the nineties and naughties with their own millions of starved peasants, slaughtered "class enemies", exiled dissidents....
The "massive industrial advantage" was nothing not to be expected from the most resource rich country on the planet.
Yet, the country was, by all accounts, from both most staunch communist party sources, and contemporary anticommunists, completely incapable of running during the crisis, and "all in" strategy of manufacturing one gun, one tank, one shell, one plane in massive amounts was a result of desperation, not industrial might.
Do not rely on state propaganda, look at the results