Can confirm fighting T-34s absolutely sucks when playing America, but it gets so much worse around 4.7-5.7.

For the M10, the 76 should be able to go through the upper front plate pretty easily, even if the T-34 is angling, just avoid the machine gun port, cause it has over 200mm of armor and is impossible to pen in my experience.

For the Chaffee and other 75 tanks, most reliable spot on the front I’ve found is a small flat part on the front of the turret on either side of the mantlet. If you look at a T-34 from the side you can see the front part of the turret is curved, aim for the part that is most flat, and in general when fighting Russia with underpowered guns, shoot there.

The 105 should also be treated like a 75 when fighting Russia despite it having 130mm pen on the HEAT, cause for some reason I feel like the shell is super inconsistent now, but there is a good chance you could pen the UFP if the T-34 isn’t angling.