The potential problem in saying it shouldn't kill a t34 is angle of attack, tank armor is designed to work on the horizontal, where sloping will deflect the round away, but let us attack at a downward angle , we are no longer shooting at sloped armor, we are shooting at it much closer to 90 degree's. and there is less likely hood of the round bouncing off.
Add to it the higher velocity of the gun and one can have a much better chance to kill, even with high explosive.
Remember a round doesn't have to penetrate to be effective, a concentrated explosion can cause spalling of the armor, with little piece of metal bouncing around the inside of a turret. Guns sights can be shattered, turret can be jammed, the thinner armour over the engine may give way, the possibilities are endless.
Then you have the theoretical effect on the crew, an artillery shell blowing up against the side armor of a tank is going to transfer shockwaves to the crew and may disable them.
Look at what is done today to provide crew protection from anti armor devices and things that go bang in general (bombs and other munitions) a lot of this wasn't even a figment in someones imagination in WW2 and so what wouldn't work today on modern tanks, may not be the same for those of the WW2 timeframe.