For God sake, problem is not in MG itself! Problem is in "how much AT powers have each side". Axis has enough AT and would have enough even without AP in MG-42. But USSR hardly suffer without early and simple AT guns, like same PTRS or DShK.
I just ask to balance AT powers of side, I don't care about MGs.
So lets compare RU AT with OST AT till T2
T1:
OH has faust,with vet1 mg42 (this will take some time)incendiary rounds (IR) and mines
RU has acces to Zis mines and is able to upgrate for AT nades.
T2:
OH has pak, schrecks and 222
RU gets su-76 and in chase of a light vehicle the AA HT as well.
The main problem with the "superior" OH AT is it needs a lot of ammunition (50 for mines, 10 for faust, 120 for schrecks and 30 for IR)+ vet. ammunition you need for other upgrates like mg42 for grens. RU has most of the time plenty of ammu for mines, sprint + AT nades due to their early strength and has a good AT gun since T1 (which has AI abilitys as well) and a maxim able to damage light vehicles.
You cannot exclude doctrinal bound abilitys like PTRS or Dshk because the are part of the game and thus need to be considered and counterable.
Concluded i would consider the AT situation balanced. GEt over it, the days of terminator T-70 are over. From now on you have to work for your victory.