Incidentally, Weasel used his 105mm guns in Katukov much better than me, I mistakenly thought they wouldn't be able to hurt T-34's because they only fire HE,so I hid mine in a huddle at the bottom of the valley and they hardly fired.
But I just ran this test below and it proves 105's are quite good against T-34's, I lined up 10 veteran guns and 10 regular T-34 Mod 41's facing each other at 200 yards and let them shoot it out without any orders from me, and ALL the T-34's were destroyed for the loss of only 1 gun, here the Russian machines are panicking and slamming wildly into reverse, chased by 105mm HE shells..
Tactical note- the guns couldn't penetrate the T-34's frontal hull armour, but they penetrated the thin turret front and the turret/hull sides without much trouble.