BUT i have to say that there is no "best tank of ww2" because during the war technique and warfare and weapons changed so often thattank warfare had to change so often. AND the military situation was so different for all this countries that there cant be parameters to find one "best tank of
faulty munition (a high number of russian tank shells burst/break when they hit enemy's armour - especially the heavy shells) and poor/bad production quality.
For the RPD, apparently just enough were made so that some saw service during the last stages of the war. It is unknown how many were given though, as large scale production of the RPD to replace the DT LMG didnt start until afterwards, and details are not that clear or available. Also if i remember right, there are details of the RPD located in german papers on observations of captured enemy equipment.The SKS is pretty much certain that it saw service in the end of WWII. there are examples in russian museums which are dated in 1945, but they were in 7.62x54r caliber, had a muzzle break type like a SVS 1936, no bayonet and a magazine that carried I think five rounds, and that a preproduction SKS run was completed in the spring of 1944as to where it was used, the only info i could find was that it was tested by the First Byelorussian Front Army used it during their entrance into eastern germany.